Whoops. Your right. I was thinking backwards. I'll fix that

 

Fixed...

Im seeing a window of 140mm to 160mm of backspace. Has any one measured this out just to confirm?

 

What about the Enkei NT03M in a 18x 10.5" +40 thats 133+40 so 173 back spacing. If that was run with a 15 or 20mm spacer it would give 153mm - 158mm of back spacing and 108mm - 113mm if front spacing.

Would this work on the the IX?

 

the pilot sport cups in a 285-30-18 weigh 25 lbs.

I still have 17 x 8's and purchased the (super sports)
235-45-17's for d.d. which weigh 22 lbs.

 

Thanks EVOlutionary for the initial review/insight - I picked up the wheels from Ravspec wrapped in R1's and I'll get'em on the track next week. To add to the light weight, CBRD Ti lugs compliment the weight and the swag.

 

Offsets? I'm at the point where I need more tire and I refuse to run spacers!!

Thanks Craig

Great thread btw!

 

Apart from not being able to rotate wheels. What is the downside of running a staggered offset setup ?? For example 18X9.5 +28 Front to avoid using spacers and 18X9.5 +34 Rear to avoid rubbing the fender. Thanx

Jay

 

To run a 315/30 Hoosier A6... do you think a 10.5 or 11" rim?

 

None.

I would say the 11" wheel. Hoosier recommends 11-12" wheel.

 

11" would be better, but they fit on 10.5"s pretty easily.

 

For the 285 Hoosiers or 295 Goodyears is a 9.5" rim needed to get the tire to tuck front and rear or with the right offset will tuck with a 10"?

 

Selecting a mass produced wheel that wide, that will clear front Brembos and rear trailing arms is a tough. The 8/9s like low offset in front and high offset in the rear. Unless there is plans to do massive fender massaging, it really takes alot to fit perfect fitting 10inch wheels on the car and still run proper tires.

 

So that makes me wonder why run a 285 hoosier on a 9.5" when a 255 on a 10" will be almost exactly the same section width.

285 => 11.5 - 0.2 = 11.3in

255 => 10.8 + 0.4 = 11.2in

This is based on tire racks posting of an industry rule of thumb, .5" change in rim width nets ~ 0.2" section width change. http://www.tirerack.com/tires/tirete...jsp?techid=200

The advantage to this being you can get the 10" wheel with a 255 to fit and have better side wall angles than the squeezed 285 on a 9.5". Same Section width but less sidewall squirm.

 

It comes down to application and purpose. For autox people jam the largest tire you can on the smallest rim. 285/30 A6's on a 10" rim is what everyone seems to run with rolled rear fenders. Some people will run 285/30's on a 10" front 9.5" rear.

I run a 255/35 Z1*Specs on a 9" rim and its pretty much square... some people run 285/30 AD08's on a 9.5" rim. And there are people that run 275/35's NT05 on a 10.5" rim.

It comes down to application of racing and how you like your tires to feel. Tires that have a little bit of stretch to them can feel a bit more crisp and responsive. Tires that bulge might have a slower response but will gain more traction in a high G corner and have less rotational mass due to the smaller width rim.

On top of that you cannot really compare the cross sectional width of tires across brands as there is not a "Standard" in measurement across all brands.

Depending on your application and your style driving will better guide you down the path of choosing tire to rim width groupings.

 

My point is if the "industry standard" is accurate the 285 is only putting down maybe .1-.2 in more than the same Hoosier A6 in a 255 (which is essentially a cheater tire as its about the same size as a 275). The .1-.2 in an extra 2% rubber but the 255 will have a stiffer side wall with less tire roll requiring less static camber improving braking...

Of course, putting the 285 on the same wheel would definitely make it wider than the 255 but were talking about what can fit under a BSP legal CT9A fender.

Also the added weight of a an extra 0.5" wheel is offset by the 2# lighter wheel. I guess Ill just have to give it a shot myself.