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[Z K]

Originally Posted by RabMcLab

Trying to look for help and inspiration led me here. Have an a 2007 e92 M3 standard wheels 19inch I think they’re the 220m style if that makes any sense to anyone. Want to go down to 18s but don’t want to lose tyre/sidewall so not sure what sizes tyre wise to go for. Looking at staggered 8.5/9.5J respectively anyone have any idea give a good figment at standard rideheight? Also not sure on offset but reckon I’ll need spacers?

Thanks in advance!

The stock 18 inch wheels are 8.5/9.5 staggered width. If that's what you are using, just use the standard M3 18" tire sizes = 245/40R18 and 265/40R18.

Why would you need wheel spacers? Just get wheels with similar offset as the stock wheels.

Here's the wheel specs for the stock wheels.
https://www.bmwoemwheels.com/en/rim-...heel-style-219

[TboneS54]

When you step down to 18" from 19", you gain sidewall, not lose it.

Spacers won't affect tires or contact patch or sidewall stiffness or any of that. Mostly looks, but also a slightly wider track. or to keep a wheel/tire from hitting a strut/spring/caliper.

245/265 is tried and true, though E46 CSL did 235/265 and many people go with that or 245/275. The numbers you see are a bit meaningless as each tire brand and model vary in their actual width. Plus tires vary in their construction i.e. stiffness. Tire width will slightly affect wheel fitment, and conversly, straightline grip. Sidewall stifness for lateral grip.

It'll be more important to chose the tire you want for the type of driving you do than worry about 235 vs 245 vs 255 etc. Pick a general size that fits the wheels, and 245/265 fits perfectly though 225-245 will fit 8.5" just fine and 255-275 will fit 9.5" just fine.

A 245 michelin ps4s can be just as wide as a 255 from another company. Tire rack will tell you the actual dimension of a specific tire.