[BMW Rolls]

I'm narrowing the wheel choices and am working on tires. Keeping the same outside diameter will protect the xDrive and I've found a fair amount of misinformation out there.

I will read the spec sheets before pulling the trigger on tires but I've been told on one particular tire a 285 in the rear is the same OD as the 245 up front, and have heard the same about 275's.

I'll solve it by looking at the tire specs myself, most are found online from the tire manufacturer.... But has anyone seen this too?

Thanks

[valbmw]

The manufacturers provide modest configs mainly 18" or 19", so don't expect to see something special from the official specs.

I am running the 20" 245/35 and 285/30. The theoretical tires heights can be calculated this way: 35% of 245 mm = 85.75 mm and 30% of 285 mm = 85.5 mm, so this is the perfect fit.

The next good couple is 255/35 and 295/30.

Also I wouldn't care on diameter differences about 1-2 mm or less. The practical tire height depends on tire pressure and normal deformation when loaded with a car body. Also wear. This will annihilate seemed influence of some millimeters on xDrive)

[BMW Rolls]

Thanks, don't think the variables you mention matter more than actual OD measurements.

Settling on Forgestar CF5 19's with Continental ExtremeContact DWS. Gave up on run flat tires and am keeping one of the old wheels/tires in the trunk in case I get a flat. Need to pick up a jack and lug wrench too. Guess I will wrap the jack and wrench in a bag to keep it from rattling.

[VWtoBMW]

The OE tire size on the 20" performance tire wheel package for an xDrive is 245/35/20 front and 275/30/20 rear. Bought the set from the dealer.