Heres the Data : 255/35/17 - OD 603.8
255/40/17 - OD 635.8 (Tires are stretched out on my 9.5" rim)
265/40/17- OD 643.3 ( No selection in 100 wear category )
Slicks-275/35/17 - OD 619.8 (available in Race only tires- Ill run this on the track because it closely matches the 255 tire OD for optimal gearing and the wider 275 tire with sticky compound theoretically should pull more G's than a equal 255 spec slick. )
100 wear- 275/40/17- OD 651.8 (16mm greater in diameter than the 255/40 set up which = ??? % amount of diminished acceleration performance but more traction in the corners which is a plus.


Conclusion : The 275/35 Slick options look promising both in gearing and increased traction potential ,The 275/40 Street tires are 16mm too tall for the gearing but possibly may be better performing in the corners due to the increased tire patch .Were looking for more cornering performance with our set up so a loss of little acceleration doest bother me .

Interested in you thoughts on this guys.

 

A 255/40 is not stretched on a 17x9.5. They may have the illusion of a *slight* stretch because of the lip protector but they certainly aren't stretched. Look at the picture I posted above, that is of a 255/40 on a 17x9.5 and the sidewalls are pretty flat.

Anyways, the tire discussion- Where would you say your level of experience is on a track? What run group do you normally drive in?

 

Refreshing to get someone else in this forum that knows what they are talking about. I concur

 

Great and timely thread.

First, to the OP and others mentioning street tires in the vein of RE-11A, ZII, etc.) the latest GRM has the new BFG Rivals beating the crap out of them all in ultimate grip & lap times, as well as communication and tolerable slip angle while still being fast.

Second. I'm getting a set of TRMotorsports C3's for my street tires (track car only, I run streets for rain and fun sometimes, and take-off slicks for fun others). The C3's are 9" wide. Would you guys think 245 or 255 would be a better choice? Tire Rack calls the 255 an 'aggressive track fitment only'.

 

245 if you want that little bit of stretch 255 if you want a vertical sidewall. I would probably look at the prices of the tires at that point and see which makes more sense.

I also agree that a 255 should not look stretched at all on a 9.5 inch wide wheel. I have a 255 on my 10 inch wide wheels and I cannot see the lip of the wheel and when I had an rs3 mounted it barely had any visible stretch to in. The RS3's run wide for a 255.

The only tires offered in the 275/35/17 size are hoosiers. If you have the money for that by all means but personally I would get used to the car with the z2's or rs3's and then move up to the hoosier.

 

The Rivals are a fast tire but according to a few of the faster guys (Psychoazn and rhouck) they are not at all worth the price premium over R-S3s. BFG/Michelin spent a lot of money getting this tire hyped up and while it is a fast tire, there are options that will deliver 99% of the dry track performance for hundreds of dollars less. We are talking very little differences here that are extracted by a professional driver.

Heat tolerance is the biggest concern for track days though, some of the EPS tires (Dunlop ZII) have proven that they are fast but overheat and fall off quickly when it is hot. So far the R-S3 has the best heat tolerance of any street tire, the RE-11 and ecsta XS are also great in this regard. If you are running them for rainy track days the RE-11A will be the best choice IMO.

The debate between a 245 and 255 on a 17x9- I run both actually. I use 17x9 with 255/40 R-S3 non staggered for summer track days and another set of 17x9 with 245/40 RE-11 for winter track days. The 245 feel better and I prefer to drive on them. I talked to a professional driver who drove an S2000 for time attack and now competes in W2W about the difference between a 245 and 255 on a 17x9 and he said the same thing, that he prefers the feel of a 245, and that testing has showed NO difference in lap times. The only difference is that the smaller tire will overheat faster. This is why so many people are moving to wider wheels, a 255 on a 10 would be perfect. Ill be using 9.5" NT03s because I don't want to spend for 17x10 Volks right now (the only option for a 10" wheel right now). If a 9" wheel were my only option I would use a 245.

 

 

Here are the pics of the of 255/40 Ventus HR2 fitment on a Volk 17x9.5". I'm not crazy about the fit, it seams a tad too narrow. I heard all the tires are different so will the R-S3,s be a little bit wider?Whats the best fitting 255/40 tire in a 40 to 100 wear category for a 9.5?
Look at the pics -now the wheel sticks out past the tire in the back by 1.5mm and is barely flush on the front face . To me who's not an expert it looks a little stretched on the front and obviously stretched on the inside face. From the experienced input I have read this Moderate "Stretch" will yield better characteristics in handling in corners which is ultimately what Iam seeking.
So according to this discussion a 255/40/17 on a 9.5 rim is the best tire size for the square set up im running considering cornering is the priority.


Can any body tell me how to simply post picture here , I have been trying with no luck

 

this

 

R-S3s and basically every other tire in the EPS tire will run wider than the same sized all-season, UHP, or Max Performance tire.

You never answered my questions above. How much track experience do you have? Going straight to an R-comp or slick if you are just starting out is a bad idea. Just because you can afford them doesn't mean you should use them.