just bought a set of wheels/tires. they are 17" with +38 offset and the tires are 215-45-17. i had the choice to go with 205-40-17 but i thought the extra cushion would soften the ride. the wheels don't completely tuck under the fender flare lip and i'm riding at stock height. went over a small dip at speed and heard something coming from the back end. are my wheels (offset) or tire size wrong for the mini. thanks.

 

It sounds like you either need to trim some inner fender liner or spat edging away or get tires that are more stretched, like those 205/40-17's you initially were thinking of. That balloon 215/45-17 isn't helping with a 38mm offset. A tire with a rounder profile would help too. This means no r-compy's or Kumho MX's or the like, but a Goodyear GS-D3 or Falken RT-615 would work.

 

my 215-45-17 MX fit with my Kosei K1 racing 17x7.5. I was running a 5mm H&R spacer on the rear, but took them off and no more rubbing at all, even over hard bumps on a lowered set up.

my offset on the rims is 45. so with the spacers I was running and et of +40 and they rubbed. My guess, with your et of +38, and that tire size, you will rub.

Might have been the wrong offset for your needs.... :(

 

put some baby powder or flour on the edge of your outer tire sidewall and
take a quick drive (in the dry, ofcourse) where you encountered the rub.

then take off your wheel and look inside your fenderliner for the white
mark. dremel that area.

i got slight rubbing at +40 running 215/45/17 7.5" width so you're
encounting another 2mm more rub. ive left mine alone cause it
doesn't rub unless i fully bump (stroke) it... and the noise is
getting smaller and smaller, meaning the tire is eating into the
liner.

 

As kenchan said there is a lot of plastic in there . Do his test and as long as you do not have to trim down to the metal you should be ok. Also check the edge of the tire itself for any cutting which would be a automatic NO NO. I get a rubbing sound now and then but I've had the same sound for almost 4 years now _