Thursday, January 12, 2012

Is it safe to drive a vehicle that has four different brands of tires?

I bought a used car a month ago and just noticed that each tire is a different brand, but each are the same size. From my knowledge I thought that each axle should have the same 2 tires one it. The dealer I bought it from said that they wouldnt replace any tires, do you think they are just saying that to rip me off?Is it safe to drive a vehicle that has four different brands of tires?
Having four different brands does increase the likelihood of problems occurring from different tire circumference. While sizes are general, every brand has different characteristics for sidewall strength and flex, actual diameter, and frictional properties. You are correct in the assumption that, at the very least, the drive tires should be matching. For front drive cars, the front tires are the most important, with all wheel drive cars and to a lesser degree 4WD cars the tires are much more important.



As anti-lock, traction control, and stability systems increase in sophistication tires become even more important. Difference in tire sizes between companies can vary enough to throw off wheel speed sensors and increase the wear on certain expensive parts such as viscous differentials (found on AWD cars like Subaru) With speed sensors the differential in speed can throw off the CPU's calculations, increasing the likelihood of loss of vehicle control. With viscous differentials a continuous speed difference can cause excess heat breaking down critical systems or materials prematurely.



Depending on your car you may have a ticking time-bomb or no problem at all, but I would never drive on four different tires in a modern vehicle. I doubt you have much recourse as far as getting the dealership to replace the tires, legal routes may cost more than the tires. (may) You can always refuse to deal with them in the future though.Is it safe to drive a vehicle that has four different brands of tires?
If the tires are each otherwise safe (sufficient tread, etc.), then it is safe. The car may handle slightly weird. For example, it might pull to one side or the other, but you can compensate for this by steering slightly in the other direction. Having matching tires is optimal, but not essential. Most drivers do not notice the difference, and it does not affect safety.



In most cases, if the cars are different brands, they will wear out at different times. Therefore, you need to check the tread depth on all the tires periodically; do not assume that they all have enough tread, just because one of them does.



On two different cars, I have needed to replace one tire on each car when the other three were good, and replaced them with a different brand than any of the other tires, and drove them for years. One car had no problems related to this (it did have an oil leak and some other unrelated problems). On the other car, the front tires eventually wore out, but that was because the car was not aligned correctly and the back tires eventually started to develop cracks in the rubber, but that was because they were almost ten years old (tires are only supposed to last for six years), and none of the problems were because the tires did not match.Is it safe to drive a vehicle that has four different brands of tires?
The brand is not nearly so important as the date code. Located on the sidewall at the far right end of the DOT codes it gives the week and year the tire was manufactured. A three digit code is prior to 2000 and a four digit code is 2000 and up. Rubber compounds start deteriorating from manufacture even though they are sitting on the shelf. Tires that are seven years old or older can suffer and have suffered sudden, catastrophic failure. Those pieces of tire tread you see out along the interstate are largely a result of old tires coming apart. Even tires right off the rack at dealers such a Sears have been found to be old, some as old as 12 to 14 years since manufacture. It pays to check before buying.
as long as the sizes are the same it shouldn't cause problems



make sure all sizes are the same like sidewall height, tread width, and rim size (I hope rim size is the same) it will be something like 225/40/R15 printed on the tire, which is treadwidth/sidewallheight/rimsize



maybe slightly different frictional resistance with the ground but nothing you would notice

and maybe some will wear our faster than the others

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