Has anyone used a 17x7.5 wheel with a 40mm offset on your Mini? I want to run as large a tire as possible (215-45-17) but am told the offset will cause it to rub the wheel wells. I was also told the 205-45-17 will rub also but I could cut some of the wheel well plastic to give them more room. Any one tried the 215s with this offset?
If I do have to cut wheel wells, how much? And does it hurt the car at all to trim the wheel well liners?

 

17x7.5" rims with +40mm offset will fit fine for a MINI with stock suspension.
If you lower the car you can get some rubbing usually in the back and especially with tires that are larger than 24.4" tire diameter.

205/45-17 should be OK with 17x7.5" rims with stock suspension. Even with 215/45-17 you should be OK and not get rubbing but sometimes the shoulders of the tires are quite square and rear camber isn't very negative so there can be minor scraping on the rear wheel well- I would predict it be minimal with stock suspension parts.

There is a How to thread on trimming wheel wells in the Performance Mod forum: Drivetrain, check out the sticky at the top.

 

Just curious, what is the object of your desire to "run as large a tire possible" that will also make you "have to cut wheel wells"? What will the extra few millimeters (mm) of rubber give you that'll make you want to have to cut your wheel wells? I say "few mm" because the tires we're talking about aren't slicks; therefore given the same tire type, they'll have proportional tread designs that won't give you an equivalent amount of more mm rubber across the tire width on as you gained in tire contact patch width (generally speaking). Of course, the contact patch isn't a thin line so you'll gain rubber for sure, but you would have to be on the edge of adhesion of the smaller tire contact patch for it to begin to make a difference. Don't get me wrong, I'm all for more mechanical grip, but unfortuately MINI's design gives you tire width limits. If you're seeking appearance I'll shut up and color. Now I'd really be impressed if you were having your wheel wells flared to give a wider birth.

Cheers!

 

By way of clarification, the reason I asked the question is because I have a new set of 17x7.5 Volk TE37s in 40 mm offset to replace my Volk GTUs.
The GTUs Im replacing are 7 inches wide with 36 MM offset. They will rub with three people in the car on bumps. (acceptible to me) When I do the math (which may not be correct) it looks like the 7.5 inch rims in 40mm will actually push the tire outboard 2mm farther, than the 7 inch/36 mm offset, given the same tires, (215-45-17 Toyo T1Rs) thus increasing the rub. I was trying to stay away from going back to 205-45-17 esp. on the 7.5 inch rims. I was told by Tire Rack 40 series tires were not an alternative because they would not "support the car". This I did not understand. So now Im really confused. If I could get TE37s in 45 or 44 offset it would cure the problem but they are not available. I don't know if this clarifies anything or not. I don't want to cut fender liners if I don't have to. Am I doing the math correctly?

 

On TireRack's "Upgrade Garage" web-based wheel/tire selector, TireRack recommends a 205/45/17 for every 17x7.5 wheel they sell for the MCS. The stock rubber size (205/45) would give you the best chance at minimizing rubbing issues. Personnally I think the 205/45 is enough tire for the MCS for street use. And if I was in the market for new tires, I'd definitely try the new Bridgestone Potenza runflat. You're not suppose to be able to tell the difference between it and non-runflats. I couldn't on the new BMW 3er.