Is there a rule of thumb when to install new C5 tires. I currently have Goodyear run-flats. I have about 3/16" thread left. I also noted on a web site that new tires have approx 5/16" thread. So I figure I have 60% wear left. Just looking for opinions.

Thanks

 

5-6 years no matter how much tread you have left...

 

3 year old tires. Any other opinions?

 

I replaced tires when I cam out of the infield at pocono north course. Spun out - did not quite a 180. Instantly corded 4 A6s (275s, and 305s) - tire to replace tires!
Was having issues with ABS. Experienced an ABS failure during hard braking at Summit Point - lots of smoke and flat-spotted all 4 V710s - time to replace tire!
if you set your camber 1.5 degrees negative you don't have to worry about an agged tire.
All kidding aside, if you are running it up to 120mph every now and then - it time to replace tires. If your driving to a car show at 50mph and drive 500 miles/year, then let em on. Don't drive on a tire w/cracked rubber.

 

Richard,

I appreciate your opinion. I have a road tour planned in July from Michigan to North Carolina with plans to do a few laps on the Lowes Speedway Race Track.

Thanks,

 

4/32's or 6-7 years...

 

My experience with RFs.........at the wear bars UNLESS you drive in all weather, 2/32 before will still get water out at speed. Any less tread and you will hydroplane at speed with the hard *** RFs......

 

When to replace your tires depends on many things

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.

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.

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.

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.

We 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!

Our 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.

Remember 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.

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 tire 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 tire, 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 and Ford Motor Company joined their European colleagues in 2005 by recommending that tires installed as Original Equipment be replaced after six years of service. (General Motors declined to offer a recommendation until a more scientific analysis of driving conditions and tire aging could be completed).

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.