Excessive tire wear: possible source

[Frankie]

...I think I'm getting more than 15k out of the tires...

...I usually burn through the rears in two summers - 10-15k miles

That's outrageously low mileage (especially for non-Sports) and only confirms my experience.

My point of reference is my trusty E39 with standard suspension. I've been getting 45K+ miles during the 7 years I've owner her. Hell, my old E36 saw similar tread life. My 'heavy' E31 would get 15K(R)/25K(F). But I can't get even this much out of my 740. BMW's really aren't so different from other cars that tire life should be problematic (M-cars excluded). It's clear to me BMW engineers sacrificed tread life on the alter of 'sport' with the E38 Sport.

Since my 740 is a daily driver, I easily see 12-14K/year...requiring new tires annually. This is unacceptable for my purposes.

[clarkitect]

Yeah I agree it is crazy low. Mine is a sport. I had an E39 sport and that wore out tires pretty fast too, at least on the rears. But being able to rotate the tires made a big difference - front to back, then side to side with the rears, switching wheels to keep the same rotation.

40k miles now with my E38 and I am on my third set of rear summer tires (one set was new but a few years old, those burned out quick), and second set of winter rears. I even had them use non-sport spec in the rear alignment.

So, yeah, I guess your basic premise is correct. But oh well, is what it is. Maybe going to a square set up would help.

[Ruskii]

Positive toe is toe-in. Those numbers look quite great actually. Does your car pull to one side? I could see you scrubbing the outer of the front right if the car had a pull and you had to steer-left compensate to keep it straight. That pull could happen as a result of tires, rather than alignment, which in your case looks great.

Car does not pull and tracks true. I am going to visit the shop that did my alignment tomorrow, and ask them to check the front. I also had them rebalance front wheels at the same time they did all wheel alignment -- maybe that's a factor to my right front excess wear (bad balance?). Tires have only 14K on them.

[nmlss2006]

Frankie,
if you recall we had the discussion back when I was having issues. I will keep this to the point: at the time I was skeptical that that amount of cross-caster could cause any tire wear and it seems that my skepticism has been validated.

I know for a fact that E38s with sport suspension from the factory did not go through a set of tires in 25k km, that is to say 15kmi. Twice that would be relatively normal, depending on a lot of factors. The difference in angles is not even remotely sufficient to have a material effect on wear (that is to say, 5% maybe?).

Driving habits, of course, count for a lot, but if you're going through rear tires in 10kmi on the street in the US... I think you may want to change them. It's not the car's fault and no, that is not normal either.

As a further point of reference, I used to go through a set of tires every ~40kmi on the M5, back when speed limits didn't matter in Europe. The last set of tires has lasted one-and-a-half times that. BMW suspension, especially the E38/E39 kind, wears tires very smoothly - when it works.

A very old mechanic a long time ago said that the best way to deal with these cars alignment is to NOT touch the factory settings. So far, in my experience, he is distressingly accurate.

[racer2086]

Grasping at straws here...Maybe try a different brand/type of tire? The E38 is a heavy car, so it requires a high load index tire. I run Firestone Firehawk Indy 500 Tires. The front is 101W and rear is 103W load rating. The wear rating is a 340. Not super soft, not super hard. Not sure if the load index plays a factor in the wear of the tires. The treadwear number (340 in my case) surely does...

[ShiftPoint]

I know this is a somewhat old thread, but I have some information to add to it.

Back in September of 2018, I bought a set of Sumitomo's for my 2001 740i sport. The HTR A/S P02's. This was at 136k miles. I replaced all of my front suspension aside from the struts and sway bar links before I bought the new tires. I didn't touch the rear suspension. Turns out the rear suspension was worn-out as well. I didn't know that until after I got the new tires...

The old tires didn't seem to have any signs of damage due to failing suspension parts or an out of spec alignment. They were just old and starting to crack. This car was a rescue lol. I was in California and it was in Michigan. I didn't even know if it ran when I bought it. None of the tires matched, one rear was on the front and the other rear was in the trunk... still had a few original spark plugs lol.

Anyways, I ordered the rear suspension parts and figured I'd park it for the winter and get back to it when spring came around... However, my plans were ruined in November. I ended up having to drive out to California from Detroit with around 600lbs of stuff on the already worn-out rear suspension and my new tires... you can imagine how thrilled I was lol.

I had to drive through a blizzard, literally at least 6 inches of snow at 65mph wit practically no visibility. I was at the edge of my seat trying to see the road. I had to turn the headlights off and drive with just the fog lights on just to see where I was going to some degree. I still couldn't see where the edge of the road was... there were no guard rails. Ended up following a tractor-trailer to a small town and got a room for the night.

I couldn't be more impressed with these tires after that... or so I thought...

When I arrived, I had to reorder the rear suspension parts. I heard that you couldn't do the wheel alignment yourself... they say it takes at least 3 guys and a donkey and even then, you'll never get the alignment close enough not to ruin your tires befire yout make it out of your garage... Naturally, I accepted the challenge lol. I figured I replaced the front and aligned it myself, so how hard could the rear possibly be?...lol....

I replaced the rear suspension by myself and set the alignment back exactly where it was. I'm almost at the 8k mile mark since I bought my tires.

This leads me to believe that you folks who are somehow managing to only get 10k miles out of your tires, are doing something horribly wrong. I see some people saying they drive pretty hard... my tires pretty much see track conditions whenever I drive...

Before I replace the rear suspension parts, the rear inner edges were worn as if the wheels were at a 45 degree angle. After I replaced the rear suspension parts, that worn-out part of the tires didn't even come in contact with the pavement. Much more even tread usage. The front tires are almost like new still.

My front sway bar link on the driver side came apart at some point, so I just removed that link, thus leaving the sway bar disconnected. I'm going to order new links, just haven't gotten around to it. I'll likely replace them before I get the new rear tires. That way, there will be no excuses not to do the wheel alignment this time.

An important thing to note... I see a lot of people talking about the Michelin pilot sport a/s 3's, but not many people actually comparing the specs. They have a tread wear rating of 500, same as mine. Max load rating of 1,708lbs, which is actually not as high as mine at 1,929lbs. The traction is rated at AA where mine are rated at A. Temperature ratings are both A, and they both have the same tread depth. However, the Michelin's have a Y speed rating where mine have a W speed rating...

I've never hit 160mph in an e38, how about you? Do you intend on taking curves at 100+mph where 40mph is recommended? I do, and I have. With no front sway bar and on my own wheel alignment.

That being said, I cannot justify buying the Michelin's, especially considering how fast they will wear vs the performance. My car has had a lot of problems, but traction was never one. If I did have traction problems, the first thing I'd do is investigate how much abuse the transmission is willing to put up with. If I liked what I found out, I'd then invest in a set of Mikey Thompson Street Comp tires... tread life will be sacrificed to the speed gods. But these have a better contact patch, softer compound, and aren't as expensive as the Michelin's.

Think about it this way... the less you have to use your brakes, the less fuel you use (because you won't have to get back up to speed) and the less often you have to replace brake pads and rotors lol.

Seriously though, when I get my new tires and alignment, I'm going to take it easy on them and report back. I'm not sure where my adventure will take me next, but for now, I'm in the mountains and thus it's only so easy I'll be able to go on them lol. Place an imaginary egg under the accelerator and pick lines that put the least amount of stress on the tires.

This new style of driving will actually be good training for the track. Extending the tire life results in fewer pit stops and thus an overall higher average speed. I'll definitely have to put some more thought into this new driving style.

[Thresher]

I know this is a somewhat old thread, but I have some information to add to it.

I will chime in too. I've had my E38 for about two years now. Shortly after purchase in June 2018 I replaced all 4 tires with Pirelli Cinturato Strada Sport AS tires. These tires are rated 500/AA/A. I've been very happy with how the tires handle but the rear tires barely managed to get 15,xxx miles on them before I had to replace them two weeks ago while the front ones are still fine and have about 1/2 of their tread life still left. A year ago I replaced two tension struts, four control arms, two rear guide links, front sway bar bushings and had the car aligned. The alignment shop reported the existing alignment was near excellent and only minor tweaks were done. Both of the rear tires had even treadwear and proper inflation. Like Frankie's original posts on this thread, I'm left wondering what to make of this.

The tire shop I purchased them from in 2018 was kind and offered a $125 per tire mileage warranty credit on a new pair of the same tires. It will be interesting to see how the replacement tires perform over the next 1-2 years as I only put about 8,000 miles on the car in a year. Prior to replacing the rear tires I made note of the DOT plant code for comparison with the new tires. Both the old and new tires had the same plant code, which when I looked it up was for the Pirelli factory in Guanajuato, Mexico.

FWIW, the remaining suspension components that I haven't touched yet are the front strut mounts, front EDC struts, the rear EDC w/SLS shocks, and rear sway bar bushings and the 4 springs. Front strut mounts and rear sway bar bushings should be easy to do; the struts and shocks are a different matter (i.e., $$$$) as I would like to keep the EDC and SLS functionality. Car has been based in California its entire life so has virtually no rust -- that gives me confidence in the springs still being in great shape and not deteriorating.