Tire Aging – Part #2

Should Drivers Replace Old Tires Even if Their Treads Aren't Worn Out?

While most drivers' past experience might not indicate it's necessary, the growing realization that tires are perishable means tires on some vehicles will possibly age out before they wear out. Composed of steel belts, fabric plies and rubber compounds, the structural integrity of tires can degrade over an extended period of time as the result of chemical reaction within the rubber components, cyclic fatigue, abuse and road hazards.

Tire aging isn't typically an issue with vehicles driven frequently. However, the lower annual mileages put on sporadically used motor homes, enthusiast vehicles driven for pleasure and collector cars trailered to events could make tire calendar age an important consideration. Tire age is also a concern for the often unused spare tire in a car's trunk, suspended under a pickup's cargo bed or hung off the back of an SUV.

Unfortunately no one is absolutely sure of how long tires will last because of the many variables. Heavily loaded tires on vehicles stored outdoors in sunny, scorching hot climates and only driven occasionally face some of the most severe service conditions and potentially have the shortest calendar lifespan. In contrast, lightly loaded tires on vehicles parked in garages and driven daily in moderate climates experience some of the least severe service conditions and potentially have the longest lifespan.

Then there is the influence of how well drivers maintain their tires (regular cleaning and pressure checks along with periodic rotations and wheel alignments), use and/or abuse them (drive on them when overloaded or underinflated), as well as the possibility of irreversible damage from punctures, cuts and impacts with potholes, curbs and other road hazards. A tire's original durability will be permanently compromised if it is uncared for, abused or damaged.

Therefore every tire's life expectancy ultimately depends on the environment in which it operates and its individual service conditions. The difficult task remains how to attempt to quantify tire life based on calendar age. Arbitrarily replacing tires prematurely based simply on age may result in tires being discarded before their time, contributing to increased operating costs, as well as waste disposal and recycling concerns.

Since Tire Rack sells tires manufactured in North and South America, as well as Europe, Africa and Asia, it's common for us to receive new tires directly from manufacturers that are already six to nine months old. Since we rotate our inventory, most of the tires we ship are less than a year old.

However some low volume tires in sizes for limited production vehicles can only be efficiently manufactured periodically where one short production run may produce more than a year's worth of global supply. In some of these cases, Tire Rack might receive new tires directly from the manufacturer that are already several years old.

There are also some occasions where we work with a tire manufacturer to help them clear out their inventory when they discontinue a tire line. While this may uncover some new tires that are several years old, these clearance tires are typically offered at a discount and will wear out before they age out.

Tires are stocked in Tire Rack distribution centers under favorable storage conditions. Protected from exposure to direct sunlight, moisture and hot and cold temperature extremes, our inventory leads a sheltered life compared to the tires mounted on wheels, installed on vehicles and exposed to the elements, road grime and brake dust.

Tire manufacturer's replacement tire warranties begin when the tires are purchased and typically last 4 to 6 years from that date. This allows the tire manufacturers' limited warranty to accommodate the time it takes tires to be shipped from the manufacturing plant to the warehouse or distribution center, to the retailer and to the consumer, as well as the time they spend in-service on the vehicle.

Keeping tires properly inflated is probably the most significant action a driver can take to prevent tire failure. For example, driving a vehicle with a significantly underinflated tire can permanently damage the tire's internal structure in ways invisible to external visual inspections. A U.S. National Highway Traffic Safety Administration (NHTSA) tire aging field study revealed that 30 percent of spare tires observed were significantly underinflated when first checked, Putting underinflated spare tires into service before being properly inflated would greatly increase their risk of catastrophic tire failure. The inflation pressure of spare tires should be checked monthly along with the rest of the set.

Vehicles equipped with a full-size matching wheel and spare tire should use the vehicle's five-tire pattern at every tire rotation. Not only will this prevent the spare tire from sitting idle, it will keep all five tires' tread depths roughly equivalent throughout their life and extend the tire replacement intervals (if rotating four tires would result in 40,000 miles of service, including the full-size matching wheel and spare tire into the rotation pattern would result in 50,000 mile replacement intervals).

The NHTSA tire aging field study also indicated a strong correlation of the speed rating with tire durability, with higher speed-rated tires losing the least capability with increasing calendar age. Drivers living in hot climates may want to consider purchasing higher speed rated tires than those that came as Original Equipment.

Our experience has been that when properly stored and cared for, most street tires have a useful life in service of between six to ten years. And while part of that time is spent as the tire travels from the manufacturing plant to the manufacturer's distribution center, to the retailer and to you, the remainder is the time it spends on your vehicle.

Tire Aging – Part #1

Nothing Lasts Forever...and Tires Are No Exception

Tires are manufactured by bonding rubber to fabric plies and steel cords. And despite the anti-aging ingredients mixed into the rubber compounds, there is a realization that tires are perishable, as well as a growing awareness that some tires will actually age out before their treads will wear out.

For the most part, today's tires deliver more miles and years of service than ever before. In the 1970s, typical bias ply tires lasted less than 20,000 miles and were only expected to be in service for about two years. In the 1980s, early radial ply tires offered a treadwear expectancy of about 40,000 miles during four years of service. And by the turn of the century, many long-life radial tires extended treadwear to about 60,000 miles during four or more years of service. While passenger car and light truck tire technology and American driving conditions in the past resulted in tire treads wearing out before the rest of the tire aged, it may not always be true of today's even longer lasting tires that are approaching 80,000 miles of treadwear.

How many years will tires last before aging out? Unfortunately it's impossible to predict when tires should be replaced based on their calendar age alone.

The U.S. National Highway Traffic Safety Administration (NHTSA) and tire manufacturers are currently studying the many variables. Exposure to the elements (sun and atmospheric), regularity of use (frequent or only occasional) and the quality of care (maintaining proper inflation pressure, wheel alignment, etc.) will all influence the answer. So while tire life depends on the service conditions and the environment in which they operate, the difficult task remains how to identify all of the variables that influence a tire's calendar age and attempt to quantify their influence.

The current industry association recommendations regarding inspecting and replacing tires due to age originate outside the United States.

The British Rubber Manufacturers Association (BRMA) recommended practice, issued June, 2001, states, "BRMA members strongly recommend that unused tyres should not be put into service if they are over six years old and that all tyres should be replaced ten years from the date of their manufacture."

"Environmental conditions like exposure to sunlight and coastal climates, as well as poor storage and infrequent use, accelerate the aging process. In ideal conditions, a tyre may have a life expectancy that exceeds ten years from its date of manufacture. However, such conditions are rare. Aging may not exhibit any external indications and, since there is no non-destructive test to assess the serviceability of a tyre, even an inspection carried out by a tyre expert may not reveal the extent of any deterioration."

More recently, the Japan Automobile Tire Manufacturers Association (JATMA) recommended practice, issued May, 2005, states, "Customers are encouraged to have their vehicle tires promptly inspected after five years of use to determine if the tires can continue to be used (recommends spare tires be inspected as well). Furthermore, even when the tires look usable, it is recommended that all tires (including spare tires) that were made more than ten years ago be replaced with new tires. Additionally, because in some cases automobile makers--based on the characteristics of the relevant vehicle--stipulate in the owner's manual the timing of tire inspection and replacement. Please read and confirm the content of the owner's manual."

Several European vehicle manufacturers of high performance sports cars, coupes and sedans identify that "under no circumstances should tires older than 6 years be used" in their vehicle owner's manual. However, it should be noted that European recommendations must include driving conditions that include roads like the German Autobahn, which allows vehicles to be legally driven at their top speeds for extended periods of time.

While American driving conditions don't include the high-speed challenges of the German Autobahn, Chrysler, Ford Motor Company and General Motors have joined their European colleagues by recommending that tires installed as Original Equipment be replaced after six years of service.

It is important to take into account Original Equipment tires are mounted on wheels and put into service right after being received by vehicle manufacturers, so their calendar age begins immediately. However the same cannot be said of tires properly stored in a tire manufacturers' warehouse or in Tire Rack distribution centers before they go into service. Properly stored tires that are protected from the elements and not mounted on a wheel age very slowly before they are mounted and put into service.

Our experience has been that when properly stored and cared for, most street tires have a useful life in service of between six to ten years. And while part of that time is spent as the tire travels from the manufacturing plant to the manufacturer's distribution center, to the retailer and to you, the remainder is the time it spends on your vehicle.

Tire Size Guide

The tire size branded on the sidewall provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability.

Our primary example will be based on variations of the 225/50R16 size, although other sizes will appear where appropriate.

"The tire size branded on the sidewall provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability."

Service Type

Most tire sizes begin with a letter or letters that identify the type of vehicle and/or type of service for which they were designed. The common indicators are as follows:

P225/50R16 91S

P = When a tire size begins with a "P," it signifies the tire is a "P-metric" size that was designed to be fitted on vehicles that are primarily used as passenger vehicles. This includes cars, minivans, sport utility vehicles and light duty pickup trucks (typically 1/4- and 1/2-ton load capacity). The use of P-metric sizes began in the late 1970s and they are the most frequently used type of tire size today.

225/50R16 92S

If there isn't a letter preceding the three-digit numeric portion of a tire size, it signifies the tire is a "Metric" size (also called "Euro-metric" because these sizes originated in Europe). While Metric tire sizes are primarily used on European cars, they are also used on vans and sport utility vehicles. Euro-metric sizes are dimensionally equivalent to P-metric sizes, but typically differ subtly in load carrying capabilities.

T125/90D16 98M

T = If a tire size begins with a "T," it signifies the tire is a "Temporary Spare" ("space saver" or "mini spare") that was designed to be used temporarily only until a flat tire can be repaired or replaced.

LT245/75R16 108/104S

LT = If a tire size begins with "LT," it signifies the tire is a "Light Truck-metric" size that was designed to be used on vehicles that are capable of carrying heavy cargo or towing large trailers. This includes medium and heavy-duty (typically 3/4- and 1-ton load capacity) pickup trucks, sport utility vehicles and full-size vans. Tires branded with the "LT" designation are the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.

7.50R16LT 112/107Q, 8.75R16.5LT 104/100Q or 31x10.50R15LT 109Q

LT = If a tire ends with "LT," it signifies the tire is either an earlier "Numeric", "Wide Base" or "Flotation" Light Truck size designed to be used on vehicles that are capable of carrying heavy cargo and towing trailers (Numeric sizes), use 16.5-inch diameter rims (Wide Base sizes) or are wider, over sized tires designed to help the vehicle drive on top of loose dirt or sandy surfaces (Flotation sizes). This includes light, medium and heavy duty (typically 1/2-, 3/4 and 1-ton load capacity) pickup trucks and sport utility vehicles. Tires branded with the "LT" at the end of their size designation are also the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.

195/70R15C 104/102R

C = If a Euro-metric sized tire ends with a "C," it signifies the tire is a "Commercial" tire intended to be used on vans or delivery trucks that are capable of carrying heavy loads. In addition to being branded with the "C" in their size, these tires are also branded with their appropriate Service Description.

ST225/75R15

ST = If a tire size begins with "ST," it signifies the tire is a "Special Trailer Service" size that was designed to only be used on boat, car or utility trailers. ST-sized tires should never be used on cars, vans or light trucks.

Section Width

Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

P225/50R16 91S

The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width. Because many people think of measurements in inches, the 225mm can be converted to inches by dividing the section width in millimeters by 25.4 (the number of millimeters per inch).

225mm / 25.4 = 8.86"

Sidewall Aspect Ratio

Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.

P225/50R16 91S

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.

Internal Construction

A letter (R in this case) that identifies the tire's internal construction follows the two digits used to identify the aspect ratio.

P225/50R16, P225/50ZR16

The R in the P225/50R16 91S size identifies that the tire has a Radial construction in which the tire's body plies "radiate" out from the imaginary center of the wheel. Radial tires are by far the most popular type of tire today representing over 98% of all tires sold.

If the R in the size was replaced with a D (225/50D16), it would identify that the internal tire body plies crisscross on a Diagonal and that the tire has a "bias ply" construction. Tires using this construction are for light truck and spare tire applications.

If the R in the size was replaced with a B (225/50B16), it would identify that the tire body plies not only crisscross the tire on a diagonal as before, but that they are reinforced with belts under the tread area. This type of tire construction is called "Belted." Tires using this construction are practically extinct.

The European Tyre and Rim Technical Organisation (ETRTO) has adopted branding standards that allowed tire manufacturers to identify tires with self-supporting run-flat constructions within the tire size designation. Self-supporting run-flat tires may be identified with the letter F immediately following the traditional letter identifying tire construction (such as the R designating radial) within the size.

This results in size designations such as 225/45RF17 91Y (for self-supporting run-flat tires that have a speed rating identified in their Service Description and 255/40ZRF20 (for Z-speed rated self-supporting run-flat tires in which the speed rating is contained in the tire size).

Since this tire size designation was adopted well after the introduction of self-supporting run-flat tires into the marketplace, self-supporting run-flat tires introduced and produced before it went into effect will not be required to be branded as such.

Speed Rating

Today, the only tires that continue to include the speed rating "in" the tire size (P225/50ZR16) are Z-speed rated tires. In this case, following the two digits used to identify the aspect ratio are the lettersZR to identify the tire's speed rating (Z) and its internal construction (R). Since 1991, all other speed ratings are identified in the tire's Service Description (which will be covered shortly).

Tire and Wheel Diameter

P225/50R16 91S

The 16 indicates the tire and wheel diameter designed to be matched together.

Tires that have a rim diameter expressed in inches (P225/50R16, as well as 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 24, 26 and 28) are called "inch rim" sizes. These are the most common types of tire sizes and are used on most cars, minivans, vans, sport utility vehicles and light duty light trucks.

While not as common, two additional "unique" types of tire/wheel diameters are still in use today.

Tires and wheels that have a rim diameter expressed in "half" inches (8.00R16.5LT, as well as, 14.5, 15.5, 17.5 and 19.5) are used on some heavy-duty trailers, heavy-duty light trucks and box vans.

Tires and wheels that have a rim diameter expressed in millimeters (190/65R390, as well as, 365 and415) are called millimetric sizes. Michelin initiated millimetric sizes for their TRX tires that saw limited use on many different car models in the late 1970s and 1980s.

Michelin PAX System run-flat tires have been introduced as an integrated wheel/tire system on a very limited basis as Original Equipment (O.E.) in North America. An example PAX System size of 235/710R460A 104T expresses tire and wheel dimensions in millimeters (235 mm Section Width, tire Overall Diameter of 710 mm and a 460A mm rim diameter, with the "A" in 460A signifying these tires feature "asymmetric" beads in which the outside bead (450 mm) and inside bead (470 mm) are actually different diameters.

All of these "unique" tire/wheel diameters were developed specifically because the tire and wheel design or intended vehicle use required them to be different than conventional tires and wheels. All of these tires and wheels feature bead profiles that have a different shape than traditional "inch rim" sizes.

Tires and wheels with unique rim diameters should never be combined with traditional "inch rim" tires and wheels.

It is critical that the tire and wheel diameters are always confirmed to match before the tire is mounted on the wheel.

Do you understand what type of spare tyre is in your trunk?

If you ever visit an auto museum, you'll see most antique cars were equipped with two or more spare tires. Fortunately today's roads and improved tire durability have reduced that necessity, allowing our vehicles to be equipped with a single spare or none at all!

While some of today's vehicles are equipped with spares that match the other tires and wheels on the vehicle, they are in the minority. Now most vehicles are originally equipped with a "temporary-use" spare tire and wheel that probably differs in size and construction from the other tires and wheels on the vehicle. And some vehicles are even delivered without a spare tire and wheel thanks to the extended mobility provided by modern run-flat tires or temporary repair and inflation systems, like the ContiComfortKit.

Full-Size Matching Spare Tires and Wheels

While full-size matching spare tires and wheels require the greatest amount of storage space, they are the most versatile. Full-size matching spare tires and wheels should be integrated into the vehicle's tire rotation pattern from the beginning. This will essentially create a set of five tires that will last longer than just four, as well as will "wear out" the spare tire before it "ages out." If the vehicle has all-wheel or four-wheel drive, the spare tire will remain at a similar tread depth to the other tires on the vehicle, reducing driveline stress when called into service. Additionally, when it is time to replace the vehicle's tires, they can be replaced as a set of five allowing you to benefit from using the latest tire technology or select a more desirable tire size that fits the original wheels.

Many of today's spare tires are temporary spare designs intended to get the vehicle to a trained tire service person to repair or replace the tire that's been punctured or damaged.

Full-Size Temporary Spares

Full-size temporary spare tires and wheels match the vehicle's original tire dimensions, but typically feature lighter-weight construction and a shallower tread depth to reduce vehicle weight to improve fuel economy and make the spare easier to install. While most of today's vehicles are originally equipped with alloy wheels, full-size temporary spares are typically mounted on steel wheels and should be used only as spares.

Temporary/Compact Spares

Temporary/Compact Spare tires are physically shorter and narrower than the vehicle's standard tires and wheels. Their smaller dimensions require they operate at higher inflation pressures (typically 60 psi) than standard tires. Temporary/Compact Spares also feature lighter-weight construction and a shallower tread depth than standard tires to reduce vehicle weight, as well as allow more trunk space to be dedicated to luggage. The compact temporary spare tire and wheel that comes with a vehicle is designed to fit that vehicle only. Never attempt to use a Temporary/Compact Spare Tire and wheel on another vehicle unless it is the exact same make and model.

Folding Temporary Spares

While folding temporary spare tires have been installed in vehicles previously, they have extremely limited application today. Folding spares provide the greatest space savings but are more complex to use because they must be inflated with an air pump or a canister of pressurized air prior to use.

The Following Tips Can Help Make Sure That Your Spare Is Used Correctly and Safely

Learn how to install the spare on your vehicle before you have to. Learn how to access the spare tire, jack, lug wrench and wheel lock key (if equipped). Confirm where the jack is to contact the vehicle and practice changing a tire. This will make it a lot easier on that cold, dark rainy night when your vehicle has a real flat.

All temporary spare tires are designed for short-term use only; they are not designed with the same capabilities in terms of load capacity, speed capability, or all-weather traction.

Always check your vehicle's owner's manual and the temporary spare's sidewall for instructions on proper use. It is also important to recognize that controlling a vehicle may be more difficult when using a temporary spare, and temporary spare tires are usually accompanied with warnings that advise against towing a trailer, or traveling over 50 miles per hour for further than 50 miles.

Check the spare tire's air pressure with a tire pressure gauge on a monthly basis, when you check all other tires on the vehicle. There's nothing more aggravating than a flat spare when you have a flat tire.

Always confirm the inflation pressure before use and ensure that your spare has the manufacturer recommended inflation. It's important to check and adjust the temporary spare's inflation to the recommended pressure before driving away.

Where to Install New Pairs of Tires?

Most vehicles are equipped with the same size tire at every wheel position. Ideally all of these tires should also be of the same type and design, have the same tread depth and be inflated to the pressures specified by the vehicle placard or owner's manual. This combination best retains the handling balance engineered into the vehicle by its manufacturer.

However due to a front-wheel drive vehicle's front tires' responsibility for transmitting acceleration, steering and most of the braking forces, it's normal for them to wear faster than rear tires. Therefore if the tires aren't rotated on a regular basis, tires will typically wear out in pairs rather than in sets. And if the tires aren't rotated at all, it's likely that the rear tires will still have about 1/2 of their original tread depth remaining when the front tires are completely worn out.

Intuition suggests that since the front tires wore out first and because there is still about half of the tread remaining on the rear tires, the new tires should be installed on the front axle. This will provide more wet and wintry traction; and by the time the front tires have worn out for the second time, the rear tires will be worn out, too. However in this case, intuition isn't right...and following it can be downright dangerous.

"When tires are replaced in pairs...the new tires should always be installed on the rear axle and the partially worn tires moved to the front."

When tires are replaced in pairs in situations like these, the new tires should always be installed on the rear axle and the partially worn tires moved to the front. New tires on the rear axle help the driver more easily maintain control on wet roads since deeper treaded tires are better at resisting hydroplaning.

Hydroplaning occurs when the tire cannot process enough water through its tread design to maintain effective contact with the road. In moderate to heavy rain, water can pool up in road ruts, depressions and pockets adjacent to pavement expansion joints. At higher speeds, the standing water often found in these pools challenges a tire's ability to resist hydroplaning.

Exactly when hydroplaning occurs is the result of a combination of elements including water depth, vehicle weight and speed, as well as tire size, air pressure, tread design and tread depth. A lightweight vehicle with wide, worn, underinflated tires in a heavy downpour will hydroplane at lower speeds than a heavyweight vehicle equipped with new, narrow, properly inflated tires in drizzling rain.

If the front tires have significantly less tread depth than the rear tires, the front tires will begin to hydroplane and lose traction on wet roads before the rear tires. While this will cause the vehicle to understeer (the vehicle wants to continue driving straight ahead), understeer is relatively easy to control because releasing the gas pedal will slow the vehicle and help the driver maintain control.

However, if the front tires have significantly more tread depth than the rear tires, the rear tires will begin to hydroplane and lose traction on wet roads before the fronts. This will cause the vehicle to oversteer (the vehicle will want to spin). Oversteer is far more difficult to control and in addition to the initial distress felt when the rear of the car starts sliding, quickly releasing the gas pedal in an attempt to slow down may actually make it more difficult for the driver to regain control, possibly causing a complete spinout.

Experience

Members of Tire Rack team had the chance to experience this phenomenon at Michelin's Laurens Proving Grounds. Participants were allowed to drive around a large radius, wet curve in vehicles fitted with tires of different tread depths -- one vehicle with new tires on the rear and half-worn tires on the front and the other with the new tires in the front and half-worn tires on the rear.

It didn't take long for this hands-on experience to confirm that the "proving grounds" name for the facility was correct. The ability to sense and control predictable understeer with the new tires on the rear and the helplessness in trying to control the surprising oversteer with the new tires on the front was emphatically proven.

And even though our drivers had the advantage of knowing we were going to be challenged to maintain car control, spinouts became common during our laps in the car with the new tires on the front and the worn tires on the rear. Michelin advises us that almost every driver spins out at least once when participating in this demonstration!

Experiencing this phenomenon in the safe, controlled conditions of Michelin's Laurens Proving Grounds rather than in traffic on an Interstate ramp in a rainstorm is definitely preferred!

Recommendations

Tires should be serviced periodically following the rotation patterns provided in the vehicle's owner's manual or as established by the industry to help enhance wear quality and equalize front-to-rear and side-to-side wear rates. The minor differences in tread depth between tires that might be encountered immediately after periodic tire rotations at 5,000-7,500 mile intervals won't upset the vehicle's hydroplaning balance and should not preclude rotating tires. For that matter, any differences in wear rates actually indicate that tire rotations should be done more frequently. Ideally tires should be replaced in complete sets. However when tires are replaced in pairs, the new pair of tires (assuming the vehicle is equipped with the same size tires all of the way around) should always be installed on the rear axle and the existing partially worn tires moved to the front axle.

While insufficient tire rotation intervals and/or out-of-adjustment wheel alignment angles often caused the differences in front-to-rear and side-to-side tire wear rates in the first place, the need to keep deeper treaded tires on the rear axle to resist oversteer conditions caused by wet road hydroplaning is important. Unfortunately this precludes the future possibility of ever rotating tires.

Once a pair of tires has been installed, the only way to escape being forced to drive on mismatched tires continually is to install a complete set of new tires (especially on front-wheel drive vehicles).

The Benefits Of Nitrogen Inflation for tire.

Tyres runs cooler, last longer and improve handling & braking. Quieter tyre - muting more road noise.

For some years, inflating tyres with nitrogen has been known to produce some substantial advantages over conventional compressed air. Its use has been limited to specialised applications such as aircraft tyres and motorsport, mainly on the grounds of cost of equipment and difficulty of generating this inert gas on the premises.

R-Tec are pleased to announce that the benefits of nitrogen inflation are now available at our workshop.

The main advantages of Nitrogen Inflation for tyres are as follows:

Tyre Inflation Pressure Remains More Stable
It is normally recommended that tyre pressures should be checked (including the spare tyre) monthly, and before any long trip. With nitrogen inflation, natural pressure loss is less and the interval for adjusting pressures is considerably extended. However, it is naturally still prudent to check your tyre pressures at the recommended intervals and particularly the pressure of any suspect tyre.

Condensation On The Inside Of Wheels Is Drastically Reduced
One of the most common everyday problems we face is corrosion on the inside of steel and alloy rims. This leads to leaking around the rim with corresponding suspicion of a slow puncture.The introduction of nitrogen inside the tyre prevents oxidization which causes a rapid ageing of the tyre and corrosion inside the rim.

The Possibility Of A Blow Out Or Explosion Is Reduced
Nitrogen doesn't heat up like oxygen, the tyre therefore runs cooler and thus reduces the possibility of explosion.

Better Grip On The Road
Nitrogen being far more stable in respect of temperature and pressure translates into better grip and improved vehicle handling. There are also proven reports of extended tyre life, making nitrogen inflation very cost effective. In addition to the benefits for most road users, nitrogen inflation has particular benfits for caravan, camper and trailer users. Better pressure retention and a reduction in the ageing process are real benefits for these vehicles which often spend a great deal of time standing in one place.

So what should drivers do?

Overall, inflating tires with nitrogen won't hurt them and may provide some minimal benefits.

Is it worth it? If you go someplace that provides free nitrogen with new tires, why not? Additionally we've seen some service providers offering reasonable prices of about $5 per tire (including periodic adjustments for the life of the tire) to a less reasonable $10 per tire (with additional costs for subsequent pressure adjustments) or more as part of a service contract, which we believe exceeds the value of nitrogen's benefit.

Rather than pay extra for nitrogen, most drivers would be better off buying an accurate tire pressure gauge and checking and adjusting their tire pressures regularly.

When Should you Replace your Tires？在什么状况下该换掉你的轮胎呢？？？

A driver's ability to control their vehicle depends on the traction between their tires and the road. Tires don't require tread designs or even much tread depth to deliver traction on dry roads. A practical example of this is the racing slicks used on stock cars and open-wheel racers that provide traction at over 200 mph. However, tires do require tread designs to generate traction on wet, slushy and snow-covered roads. Liquids can't be compressed and require time and energy to move them out of the way as our tires drive through them. Those same racing slicks would lose traction at amazingly slow speeds anytime something prevented them from maintaining contact with the road.

So a tread design is necessary to direct water and slush from between the tire and the road, as well as provide edges that bite into snow. But that's only half the equation; because we've seen that tread depth also contributes to how well the design does its job.

The air our tires encounter at highway speeds can easily be compressed and moved out of the way with relative ease. However the same isn't true of liquids. When water collects on the road surface during rainstorms, the water depth, vehicle speed and vehicle weight, as well as the tires' tread designs and tread depths collectively determine when and if the tires will be forced to hydroplane and how quickly they can stop a vehicle.

"Tire Rack's advice is that if rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32" of remaining tread depth."

A typical passenger car tire has about twenty square inches of total footprint surface and begins with about 1/3" of tread depth. While the majority of the footprint surface is made up of the rubber that grips the road, the remainder is the void of the grooves that make up the tread design. (See Photo #2)

In order to confirm how much wet traction worn tires sacrifice, members of the Tire Rack team measured the stopping distances from 70 mph (the typical speed limit of U.S. Interstate highways) with vehicles equipped with sets of new tires and compared them to tires with about 4/32" (3mm) of remaining tread depth, followed by sets with the legal minimum of 2/32" (1.6mm) depth. The differences surprised us! Vehicles equipped with the 2/32" minimum tire tread depth took about 100 more feet to stop and were still traveling at about 45 mph at the same distance the vehicles equipped with the 4/32" deep tires had already come to a complete stop!Obviously the tread will wear away over the life of the tire and the volume of its tread grooves will be reduced. While this occurs so slowly that it may not be noticed day-to-day, ultimately there will be a time when the driver will notice the car slip in the snow, hydroplane in the rain or simply not stop in as short a distance on wet roads.

The Tire Rack's advice is that if rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32" of remaining tread depth. Since water can't be compressed, you need enough tread depth to allow the rain to escape through the tire's grooves. If the water can't escape fast enough, your vehicle's tires will be forced to hydroplane (float) on top of the water, losing traction and increasing stopping distances.

Additionally, if snow-covered roads are a concern, you should consider replacing your tires when they reach approximately 5/32" of remaining tread depth to maintain good mobility. You need more tread depth in snow because your tires need to compress the snow in their grooves and release it as they roll. If there isn't sufficient tread depth, the "bites" of snow your tires can take on each revolution will be reduced to "nibbles," and your vehicle's traction and mobility will be sacrificed.

While replacing your tires before they are legally worn out may not appear the most economical practice, it is far less expensive than repairing your car if it can't stop in an emergency situation in less distance than the vehicle ahead of you!