tire question

I have a 2010 - 328xdrive with 28K miles on the tires. Tire Question: When you need one tire replaced, should you buy replacement tires in pairs to match 2 similar tires either in front or back? Should new one(s) be placed in front or back? Many Thanks for feedback.

Pairs & fronts

New tires should go on the back & the worn back tires moved to the front. Its counter intuitive but its the best way unless you are running bigger rear tires.

And just to confuse matters further, we replaced two tires on my wife's 328iX and the car drove like crap... Only after we replaced the remaining two tires, did it drive well again... Supposedly there is a limit as to how much of a variance there can be in tire height (front to back) otherwise the DSC gets confused, or something to that effect...

Originally Posted by BMWtje

I have a 2010 - 328xdrive with 28K miles on the tires. Tire Question: When you need one tire replaced, should you buy replacement tires in pairs to match 2 similar tires either in front or back? Should new one(s) be placed in front or back? Many Thanks for feedback.

New tires should ALWAYS be put on the REAR....NEVER THE FRONT when there are worn tires.
NO tire manufacturer recommends new tires on the front when only two tires are replaced. If only one tire is replaced, it should go on the REAR, mated with the tire of the highest tread depth, but the SAFEST option is to put two NEW tires on the rear.

This has to do with unsafe "oversteer" in WET conditions with worn tires in the rear. If you have any doubts about this...or if your local installers have any ridiculous "wive's tales" that say otherwise, I'll send you about a dozen horrific product liability death cases where "new tires" on the front resulted in deadly accidents. Sorry to be so graphic.

Originally Posted by bear-avhistory

New tires should go on the back & the worn back tires moved to the front. Its counter intuitive but its the best way unless you are running bigger rear tires.

It makes no difference if you are running "bigger" rear tires. New tires on the rear ALWAYS.

Excuse me but I have 275X30X19 on the back. They will not fit on the front which has 245X35X19. Neither would the factory stock 255X30X19.

go for 4 new tires

Originally Posted by bear-avhistory

Excuse me but I have 275X30X19 on the back. They will not fit on the front which has 245X35X19. Neither would the factory stock 255X30X19.

Staggered fitments sometimes pose a problem when the front tires wear out before the rear tires...and the rear tires are still good. This happened on my E92. I wasn't about to put two new tires on the front. These were my original (OE) tires.

After some "negotiations" with the tire manufacturer, all four tires were replaced on a "shared cost" basis.

Agree, I usually change all 4 if they are close, so far have been OK with that.

Originally Posted by pointandgo

Staggered fitments sometimes pose a problem when the front tires wear out before the rear tires...and the rear tires are still good. This happened on my E92. I wasn't about to put two new tires on the front. These were my original (OE) tires.

Shaving is another option in unusual cases such as this. I once had two wheels and tires destroyed by a road hazard and had the replacements shaved to match the average tread depth of the undamaged pair. The $50 charge for shaving paid for itself a dozen times over.

Originally Posted by Salvator

And just to confuse matters further, we replaced two tires on my wife's 328iX and the car drove like crap. ... Supposedly there is a limit as to how much of a variance there can be in tire height (front to back) otherwise the DSC gets confused, or something to that effect...

You are exactly right; there is nothing supposed about it. It's not just front-to-back difference, either; the rolling radius of all four corners needs to be within tolerance relative to one another (hence my shaving adventure).

Thanks for all the great replies. I will go with 2 new tires on the back. The remaining 2 on the front will be at 6/32, so should be good for another year, unless the DSC gets 'confused'.

The allowable difference in diameters across an AWD system varies by manufacturer. IIRC, Subaru allowed a 2/32" difference in tread depth across the car and VW allowed a 4/32" difference. My wife's old Subie required you to pull a fuse to disable the AWD function if you were running on the T-spare tire, and my daughter's Passat has a full-size spare as a consequence of the above. The tread depth difference bit us when my daughter damaged on tire on a half-worn set of 4 on her 4motion Passat. We replaced one tire and had it shaved through TireRack to be able to get the whole set in spec.

The problem with xDrive cars is that I have never been able to find a BMW specification for the difference allowed. You would think a German manufacturer would want you to know something like that, but no.

Thanks, I will check with the dealer and perhaps buy 4 new ones......