[Weeknd]

I did get a flat tire and it was not repairable so i had to buy 1 tire for the rear
So basically my left rear is 7\32 and my right rear is 10\32
im RWD with the M235i
Is it a big difference, is it bad and what will happen?

[msej449]

Re braking distance, no and yes: Performance tires often have an inflection point - a depth below which they degrade disproportionately. Usually around the 4mm (3/16", 5/32") point. Below this depth, the braking distance start to get much worse. So for example, if one tire is at 5/32" and the other is at 2/32" then there may be a noticeable difference in the braking ability of the more worn tire. So for a start, once your more worn tire gets to 5/32" then change both.

As for handling, it's more difficult to generalise, not least because of differences in individual products. Personally, I'd always replace both tyres when one goes, and always have. But that's been where both were fairly worn anyway.

[rhop101]

I ended up hitting a pothole last October and having both tires on my right side get crunched. Probably just going to get a fresh set either just before or just after O’fest when I get my next oil change since the other 2 tires are original on my 2015 pretty sure. Mainly the thing I see just cruising is that they’re is some jacking going on as the tire pressures and temps are always higher even though they’re equally inflated cold. Haven’t noticed any weird handling or braking while autocrossing or on the street, but 15k miles difference on a set of PSS is what I’m dealing with.

[BEM-S4]

Would be a good question to post in the wheel and tire subforum.

[NVHoo]

The general guidance is that if it is an X-drive, all tires should be within 2/32 or the differentials will have to work more than they should. If it is RWD, put the dissimilar tires on the front so the differential is not effected.

[Weeknd]

Ok but for my case now 7/32 and 10/32
What will it do?
Is it bad for differential?
Is it bad for alignment?
Is it bad for control?

[NVHoo]

Bad for differential. Not noticeable for control until the tires wear to near replacement because, as previously posted, braking on the dissimilar tires will be different and, to a lesser extent, handling. Has no effect on alignment whatsoever

[smchuck]

why not get the new tire shaved down to match the tire on the other side? TireRack will do this when you order from them.

[aerobod]

The standard staggered tires fitted to xDrive F22s are 225/40-18 front and 245/35-18 rear. The nominal diameter of these two tyre sizes is 8.5mm different between the front (larger diameter) and rear tyres, so any tread depth difference is likely to be less than the tyre size difference on new tyres. Just keeping the tread depth even side to side is needed, it doesn’t matter about front to rear from a centre differential or transfer case perspective if the rear tyres have more tread than the front ones.

[Unicorn123]

OP,

Rotate the rears to the front and vice versa, assuming you are running a square setup. Then it will not make a difference to the differential. All fixed.

The variance you describe is ~0.8% in rolling diameter; I am not an expert on differentials, however I expect this is likely a non-issue from a practical perspective, if you are not running a square setup. If you are concerned, find a shop that will shave the tire to the correct circumference, or buy a second new tire to solve the problem.

[Weeknd]

I am not running a square setup
Like aerobod said its bigger tires in the back 245 35 18
Front is 225 40 18
Nobody shaves tires in my city ill try to call a few places cause i havent found any

[Shovelman]

The ring and pinion gears run at high speed for the life of the car. They rarely fail. When a wheel is on ice it is easily possible for the spider gears to run briefly at pinion gear speed. They are made similar so they can take some hard use. They rarely fail. You are considering whether running them at 0.8% of pinion gear speed will harm them. Definitely not.

[2016M235i]

The difference between 7/32 and 10/32 will not cause premature wear of the differential. Unless you are travelling on a perfectly straight road, one rear wheel is always turning at a slightly different rate than the other one anyway. The differential is built to accommodate this.

[chattanooga240]

Premature tire wear is what you are looking at, no extra mechanical wear though.

I don't think it's life and death, but I'd buy another tire and keep that 7/32 as a spare.

[Weeknd]

in rain yesterday i went from 15mph to like 40mph fast with it and the traction would kick like crazy it didnt do that before....
i think cause one tire is bigger its make the car drift more in the rain
could have be possible?