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I have a 2002 Infiniti Q45 I bought used some number of years ago. It came with clearly two pairs of tires (both were the same brand/type) installed at different times. So, over the years I have always been replacing one of the two pairs as they wear out. Probably about 10,000 miles apart.

Note that tire rotations are done along with other maintenance and repairs, but my mechanic usually keeps the pairs together, though the tires have always been the type that only specify which side goes on the outside, so not rotation specific.

If you are not aware, this car is RWD with 4.5L V8.

It has always felt like the rear tires wear out more rapidly than the front, but I've never actually tracked it, so I'm wondering if my intuition is completely off-base and what are the actual factors in tire wear? Is it braking? Steering? Applying power? Something else?

  • Good question! Since braking is close to 50/50 (actually the front tires brake a little more), and only a tiny amount of the total energy used goes to the brakes during normal driving, I think we can pretty much eliminate braking as the cause of uneven tire wear. – juhist Jan 29 '17 at 17:16
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    Braking isn't close to 50/50 on any car I've ever owned, I just replaced my second set of front pads, the rears still have plenty of life (despite being slightly smaller pads than the front) – Johnny Jan 29 '17 at 18:43
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For the most part, the front tires will wear faster than the rear tires. This is due to having to steer the vehicle. When the car is moving, you put steering input through the steering wheel, this sets the tires in motion to change the direction of the vehicle. When direction change occurs, the tires must fight the inertial forces as the car wants to keep moving in the same direction. The tires provide the means by which to get the car going in the right direction. Everytime this happens, a little bit of tread is left behind. Albeit it's a very small amount, but there's more left behind than if you were just going in a straight line. Throw in the fact the front tires change alignment (due to caster/camber) while turning and with Ackerman adjustments thrown in, it takes its toll. If you have the suspension setup correctly, this wear is kept to a minimum, but it still occurs. This happens moreso when the vehicle is a front wheel drive due to the pulling forces which occur as well. The rear tires don't suffer as much as the front. For the most part they follow the front tires and live a fairly pain free life. There is a slight bit more wear on the rear tires on a rear wheel drive vehicle, but it still doesn't come close to the wear of what happens up front. The only caveat here is if you get a little feisty with your car, doing burnouts and such. That'll put a lot of wear on your rear tires very quickly.

All-in-all, the whole reason for doing tire rotations is to prevent uneven wear and hopefully to get all of the tires wearing around the same rate. In your case, only replacing two at a time may be a good thing, as the cost of replacing them gets spread out a little more.

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Tyre wear is caused by many factors. Your driving style, the tyre's pressure, the car's weight distribution, the design and setting of the suspension(especially camber) to name a few... This might vary per tyre on your vehicle. It's hard to tell. Keeping your tyres inflated with the prescribed pressure, and checking your suspension's aligning evey now and then will reduce tyre wear. Inflating them more may get you some fuel economy, but it also may cost you some traction, and it may wear the tyre more in the middle of the running surface of the tyre.

In my car(also RWD), all tyres wear at the same rate. In my other car, the front tyres wear a lot more than the rear tyres. In both vehicles I use the same Vredestein All-Season tyres.

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