255/40/17 set up

[FRSToyota86]

Would my 17x9 42mm offset fit 255/40/17 with coil-overs without any rubbing issues?? Thanks for input

[CSG Mike]

Originally Posted by FRSToyota86

Would my 17x9 42mm offset fit 255/40/17 with coil-overs without any rubbing issues?? Thanks for input

You'll most likely need spacers, and possibly extended studs to accommodate the spacers, depending on the spacer.

[LOLS2K]

Originally Posted by CSG Mike

Oh it can heat up a 255. It's just a matter of what your goals are. 225 generally yields faster lap times, but it's not always the case.

Why?

[CSG Mike]

Originally Posted by LOLS2K

Why?

You should read a lot of my posts from 2012 and 2013...

short version: less rotating mass

[LOLS2K]

Originally Posted by CSG Mike

You should read a lot of my posts from 2012 and 2013...

short version: less rotating mass

I ask because coming from the S2000 world, 255 square is VERY common. I also see many FI FRS/BRZ drivers sticking with sub 255 tires due to faster lap times.

[redlined600]

Originally Posted by LOLS2K

I ask because coming from the S2000 world, 255 square is VERY common. I also see many FI FRS/BRZ drivers sticking with sub 255 tires due to faster lap times.

There is a lot of discussion of this(which leads to "cause I read it on the internet" but I doubt many have tested back to back (wide vs skinny) to prove this out. In addition it's likely track dependant.

[CSG Mike]

Originally Posted by redlined600

There is a lot of discussion of this(which leads to "cause I read it on the internet" but I doubt many have tested back to back (wide vs skinny) to prove this out. In addition it's likely track dependant.

It's easy to get a large data set when you have 86CUP locally

[redlined600]

Originally Posted by CSG Mike

It's easy to get a large data set when you have 86CUP locally

Fair enough, do you have any data you can share?

[CSG Mike]

Originally Posted by redlined600

Fair enough, do you have any data you can share?

I shared the conclusion, which is that skinnier tires are almost universally faster when the driver equation is taken out.

Unless you have a course that is almost exclusively under cornering load at low speeds, you lose more than you gain with fatter tires.

Assuming your driving skill is at the requisite level of course

For those that are not as experienced, the lower limits also make for a more forgiving car, that also offers more opportunities for driving at the limit.


I'm neither at liberty to release CSG's data, nor client data, without expressed permission... sorry!

[philooo]

I have 2 sets, one in slicks 245 on 17 rims BFGR1
and another set 225 on 17 ADV08

I can tell you that I run the exact same times at homestead, and I prefer the 225 progression.

225 I think are faster, 245 feel faster because you can take tighter turns.

[Rifle]

Not track use, but I have Ambit RE02s 17x9+35 (RPF1 specs) wrapped in Continental ExtremeContact DWS06s 255/40s. Had no fitment issues at stock height. Lowered the car about 2-2.5inches and had minor rub in the rear with stock LCAs (-2.5deg camber) so I raised the height accordingly instead of rolling fenders. Done deal.

[OkieSnuffBox]

Originally Posted by kster1

OP, slightly off topic but you should check out the December issue of Grassroots Motorsports. They talk about the relationship of rim width and tire width in their lap time results. The conclusion was that:


"The optimal rim size for a tire is equal to, or slightly larger than, the tread width."


According to their testing, a 255 tire is not ideal for a 9" rim.

GRM was just publishing what those of us in the Miata community have known for years. 949 and Trackdog have shown this for a long time.

Granted Rcomps run wider, but we typically run:

205 on 8"
225 on 9"
245 on 10"
275 on 11"

My Miata from years ago, 205 R888s on a 15x8.

[zdr93523]

Originally Posted by SubiePig

I run a 17x9 +35 with 255/40/17's I have no fitment issues but I am not sure if the same could be said for a car on stock suspension.

How much camber are you running? and is it by way of plate or bolts?