[TrboMike]

Now that I found a hole in the sidewall of my horrible OEM RFT the slow research into new rims and tire just became a priority. Should blow and lose pressure any day now.

My goal is 245/35-18 on 18x8.5 square. Wheel websites all say smaller tires must be put on XDrive F22's for less room but they never say WHY. I know the fender is in the same place between RWD and XDrive, so either the alignment/camber is different (not likely) or the hub location is further out (so XDrive would be wider tire stance in front comprated to RWD?) or the most likely situation is the spring/strut setup is wider and hencer closer to the rim and or tire for XDrive.

I found on this forum plenty of RWD guys using 245/35-18 on 18x8 and 18x8.5 with offset between 38 and 44 but the only XDrive guys I can find are using a tire size and offset that is EXACTLY the same distance to the suspension as OEM. I cant find anyone XDrive who is even 1mm closer to the suspension, but I have seen people say 8wide is ok for XDrive front but 8.5 wont work. But they never mention offset.

I'm willing to get an 18x8 square but I still want 245/35-18. If I get 18x8.5 the perfect offset to keep OEM rim/tire distance would be 39mm but theb my tires would be 23mm closer to the fender and rubbing on bumps could be a real issue. Also +39 rims dont exist without going custom so I'd probably be in a +38 offset, another MM closer to the fender.

If I go with 18x8 then I could go with +43 offset and only be 19mm closer to the suspension, and I've found other guys who had tires 18mm closer to the suspension and claim no rub on OEM ride height and alignment.

I think a perfect rim for me would be 18x8 +45 which would put the rim 2mm closer to the strut and put a 245/35-18 17mm closer to the fender.

BUT will that 2mm closer to the suspension be a problem? That is the question.

[Maynard]

Kind of a confusing post there, and not sure your math is correct, are you using a calculator/'willitfit' program? I'm running 245/35-18 on 8.5 et40 wheels in back, no rubbing (Xdrive). In front are 8.0et40 w/225/40-18 so can't say it will fit there. If you go to 8" square you'd certainly be better off w/ 235 width in terms of handling/dynamic response.

[TrboMike]

I'm putting in whats others have posted as working/not rubbing and comparing to to the OEM wheel/tire to see how much it has moved toward the suspension and how much it moved toward the fender. Then I know what will fit and what will rub.

Then I switch the calculation to a 245-35/18 tire on various offset wheels to see exact how much that will move to and from the fender and suspension and compare those to known good fitments above to see what offset wheels I need to order to get that tire to fit in the front.

The problem is most of the data is for RWD so I dont look at those, and most of the XDrive who do most their specs are using small front tires so that doesnt help me either.

So far I know I can get an offset wheel that will be the same distance from the suspension as OEM, and can go out 18 to 20mm to the fender and still not rub. The question is how many precious millimeters I can get the setup I want to the suspension to get more room to the fender for a big 245/35.

[Maynard]

Have you tried one of these calculators for working this out? I would be cautious about what people put up here as 'fitting great' - sometimes they might be missing rubbing (or don't drive fast enough on bumpy roads or curves to find out). http://www.tire-size-calculator.info/

[KennyFSU]

Xdrive here. I'm on 18x8 +40 wheels, currently stock RFT 225/40 but I'll be getting 245/35 once the stock ones need replacing. No spacers, no rubbing.

[TrboMike]

Yeah I'm using a calculator. Ugh I read the OEM wheels are +52 offset but that is only for the rears if you're staggered. Square and all front rims are +45 offset.

That changes my calculations of 245 fitting in front.

Kenny- why do you think the new 245's will fit? The rim itself will be ok but the 245 at that offset will be 5mm closer to the suspension. I havent found anyone who says they're running that close without issues and needing spacers.

[Expert@ApexWheels]

In our experience, the fitments between the xDrive models and the RWD cars are the same with respect to what wheel and tire packages will clear.

With our wheels we have 2 different 18x8.5 wheels that can work, either ET35 or ET45. For 245 section tires, the ET35 square setup requires additional negative camber front and rear to fit without rubbing while the ET45 setup requires a small spacer in the front (5mm) and a bit of front negative camber but no additional negative camber in the rear.

Either option can work and it is a bit of a trade-off at the end of the day. More info about these options and specs can be found here: https://support.apexraceparts.com/hc...-Fitment-Guide

-Tom