Tyre Wear

[Minny]

I appreciate tyre wear is fully dependent on so many factors but I would like to get a handle on what is reasonable tyre wear on my car.

I have 20 inch M Sport rims and run 32psi all round. The 4 wheel alignment has been checked and nothing untoward has been found (no abnormal camber or excessive toe-in on the front)

My front Dunlop SP SPort Maxxs only lasted about 12k miles before the outer edges were worn to 2mm and the rest of the tyre about 3mm. I now have Bridgestone Dueller H/P Sport on the front and after 10k miles it appears the outer edges are wearing quicker again (about 5mm and the rest of the tyre 7mm).

The rears are still on the original Dunlop Sport Maxxs and have worn fairly evenly with just under 3mm tread after 22k miles. They will be replaced with Bridgestone DUellers in the next week.

Thanks in advance for any advice/views

[phatr1s]

I have the same issue with my stock tires (19 inch Michelin) with 20k miles, I looked for tire information, and I found out the outer edge worn is due to low psi or hard cornering. I played with the psi settings and I noticed for my running 35psi all round they may last longer.

[ard]

WHAT ARE THE ACTUAL ALIGNMENT NUMBERS????

The allowable BMW spec is so large that you will see a two fold variation in mileage between the alignment extremes! So just 'checking to see if it is in spec' is woefully inadequate.

[Minny]

The rear camber was -1.5 degrees and left toe in was 10 minutes, right toe in 8 minutes.
The front camber was -0.5 both sides and total toe in was 15 minutes.

[ard]

I'd want the toe on the rear closer to zero, maybe 2minutes. Front at 2-3-4 minutes (or 0.01-0.03" front; 0.01-0.02" rear)

Camber looks OK.

I run 36 psi fronts but those are different tires. I run 34 in the rear as I rarely carry loads.

[Minny]

Thank you. I did think of reducing the front toe in to 5 minutes as the steering seemed sharper

[ard]

As you think of it, "toe" is simply 'twisting' the tire contact patch in relation to the roll direction. It simply scrubs the tire against the road. "perfect" is zero.

But zero may give you other issues, plus sometimes under load the suspension alters. So you need SOME toe.

In ALL my road cars I set toe to the absolute minimum allowed by the mfg.

[JCL]

I would set rear toe to the minimum spec, no question.

The issue of front toe is a little different IMO, as too little can make the car feel nervous, or darty.

I always remember reading this from Tire Rack, on the impact of toe settings:

Originally Posted by Tire Rack web site

Consider that if the toe setting is just 1/16-inch off of its appropriate setting, each tire on that axle will scrub almost seven feet sideways every mile! Extend it out and you'll discover that rather than running parallel to each other, the tires will scrub over 1/4-mile sideways during every 100 miles of driving! Incorrect toe will rob you of tire life

There is a lot of (too much, IMO) focus on negative camber, because it is so visible that people think it must be a problem. But it is designed in for a reason. On the other hand, just think about the impact of the tire scrub sideways over 10,000 miles of driving, using the above figures. It is like doing a 25 mile sideways skid. That is what destroys tires early.