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I'm have slight traction problems in first gear on my pump gas 442whp tune. With e85 it's over 600whp so first and 2nd gear is useless. I.m currently on ap2v1 with rs3's (225/45 and 255/40). I want proper fitting s2000 spec wide rims such as 949 17x10+72 or volk ce28 17x10+70. I believe these 2 rims are the only correct fitting 17x10 s200 rim. 949"s are impossibl to find. And the Volks are $4000 and discontinued. So I decided to widen the stock rim.
I want to run 255/40/17 nt05 on the front with stock rear rims and 275/40/17 on the back with widen stock rims.
I plan to go there to widen my stock ap2v1 rear rims from 8.5 wide to 10" wide. When they do this the extra width in the back end so the front will not sit any closer to the fender. So the stock rime would be 17x10 +84 ish I think? Are my calculation correct? I want to run the smallest wheel spacer possible. So a 15mm spacer would bring me down to +70. Perfect for the stock body. Is this correct?
Is this a good idea? Has anyone done this? Should I make it 17x10.5? How about the kumho xs 295-35-17?

BTW. I hate stretched tires/ hella flushness and super aggressive negative camber. I don't want to run over fenders but I will roll the stock fenders if I absolutely have to. I'm also on stock suspension/ ride height and I'm staying this way.

 

Your calculations are incorrect. Widening the OEM rear to 10" would make it +74. The only concern I'd have is inner clearance. Have you gotten under there and measured?

Another user, S2000Junky widened his 9 +45 RPF1's to 11.5 and mounted the 295 kumho tires, and it's literally as wide as he could possibly be without needing crazy camber. His fenders are also rolled flat, and he's said it's impossible to be any less aggressive because it'd hit suspension on the inside.

The same 295 on a 10.5 wouldn't work because of the bulge, and it would actually be too far inset since your setup would be much less aggressive than his.

If it were me, I'd explore the idea of going 10.5 and running a 265/40. You might have to run a 5mm spacer for clearance. I'd also get under the car and measure some of this stuff out

 

Your calculations with a stock wheel widened to 10" were correct. 15mm spacer would probably be the way to go, may need a slight fender roll depending on your ride height and alignment settings. I couldn't say exactly how much room is on the inside, but you could get away with less than a 15mm spacer, 10mm would work for sure and maybe even 5mm. There is a ton of room on the inside, I'm running a 11" +64 and there is still a little to work with.

I would stick with 275/40. The diameter isn't ideal, but really there aren't many choices when you go wider than 255. 295/35 has been done but needs a full fender roll and offsets that take advantage of all clearance down to the mm. Only 1 tire available that I know of in this size.

 

^Nate how would that work? Isn't the stock wheel 8.5" +55? I was running the math with that assumption of the OEM 17" specs. If that is the correct OEM spec, then adding 1.5" on back side of the wheel would make the final specs 10" +74 right?

 

Stock rear is 8.5" +65.

 

Stock is 17x7+55 in the front 17x8.5+65 In the back.

Should I make the rims 17x10 or wider? A 275-40-17 is the tire size I'm going to run.

 

I would widen the front wheels and move the rear wheels to the front.

 

Wow I never thought of that. Do the front wheels bolt up to the rear with out problems? I know to put the rear wheels on the front you need to with run a 5mm spacer or bore out the center hub of the wheel. But what about puting a front wheel on the rear?

If I widen the stock 17x7+55 to a 17x10 the offset would be +92 so a 20mm spacer would be perfect for the rear.

 

You are correct. You'll need at least 5mm spacer for the rear wheels or bore out the center bore. You should be able to run a 255 in the front even with the spacer. (not sure if you'll need to roll or not since I rolled my fenders a long time ago)

The front wheels fit a-ok on the rear. No spacer requried, but of course you'll be running one anyway to get your offset right.

 

295 35 17 Kumho Ecstas are pretty much impossible to find at this time just so you know.