Haven't seen a lot of info on this matter.

Anyone using the 255x35x20 Michelin Pilot Super Sport up front? I know the 305's will fit in the rear without problems, just wondering about clearances up front.

Thanks in advance.

 

I have the Pirelli PZero's 255/35/20 (F). No rubbing and looks a lot better than the stretched out look of the 245's (an opinion, of course).

 

I also have the 255/30x20 MSS on the front. No issues with rubbing, and yes they do look better.

 

Thanks to both of you for the replies. I would have thought more people would have made the upgrade, but no worries.

 

Track: MPSS 265's in front; 305's in rear; BBS 20" - 9's & 11.5's

Street: Dunlop Sport Maxx 255's in front; 325's in rear (will change to 265's in near future); HRE P40 SC's 20" - 9.5's & 12's

 

Interested in your specifics here. I currently run 19x9" front wheels with 255/35-19 tires, and 19x11" rears with 305/30-19 tires. This is with Yokohama AD08Rs, which have been very good so far on the track, and also satisfy my daily driver/wet weather needs. But now I'm itching to try the new Pilot Sport Cup 2s, or PZero Trofeos, neither of which come in the above sizes. I would need to do 265/35-19 fronts and 325/30-19 rears. A 265/325 combo is probably better for the track, but I'm worried about running those tire widths on 9 and 11"-wide wheels. The Michelin and Pirelli specs suggest that a 9.5"-wide wheel is more appropriate for a 265mm tire, and an 11.5" or 12"-wide wheel is more appropriate for a 325mm tire. Based on this, I was thinking of sending my 3-piece wheels back to Forgeline this winter so they could change the outer rim halves to 0.5" wider pieces. This would keep my inner clearance the same while increasing overall width by 0.5".

But you're running 265mm fronts on 9"-wide wheels. Are you getting any sidewall rollover with this setup on the track?

 

And the 255/35/20s are also less expensive than the 245s.

 

255-35-20 front also.
Highly recommended, especially if you have the 9" Sport Techno or Sport Classic.

 

Feel free to pm me if you want more specifics... I'm sure that there will be the Koolaid drinkers on this forum who will say "No way that a 265 will work; Why would you want to go to a 265?; You'll get too much understeer; You'll get too much oversteer" etc., etc.

Long story short, I have thrashed the 265's on 9's with NO rollover problems OR rubbing at 1.57 G's. However, my tire temps and wear patterns indicate that I need to change out my suspension with adjustable control arms and wishbones (Elephant Racing) to get more negative camber (I maxed out only @ -1.4 on the front) and there is NO adjustment for caster on the 991. However, as you know, I won't be tracking my 991 again OR spending any suspension $$$ until the PDCC / PASM software issues are resolved first.

Depending on your Forgeline offsets, you might have enough fender clearance if you add 1/2" more front spacing with larger outer rim halves (If you measure out the exact clearance from your fenders, this is a visual reference and cannot guarantee enough room, esp on the front, without the manufacturer having first tested the offsets). Better for you to use actual spacers equal to 1/2" to test the exact fender clearance with the Forgelines before you send them away (why not use a couple of Porsche threaded aluminum wheel alignment rods so you can temporarily place the wheel over the spacers without having to get longer wheel studs?)

My one-piece BBS CH-R's are not aggressive at all and could absolutely use more negative offset (e.g., there is too much back spacing). In other words, the wheels do not fill the fender so it appears that I could easily add 10-15mm spacers front and rear to increase the negative offset.

My HRE P40 SC's on the other hand are an aggressive offset and there is much tighter clearance with the outer fenders F and R. As you know, it's not just looks but also handling...

 

???????
Tirerack

245 = $277
255 = $309

 

And the 255's on the front work with S-PASM?

 

If 265's work for me with SPASM, then absolutely, 255's will work for you!



2014 Agate C4S w/: X51; SPASM; PDCC; Akrapovic exhaust; black ceramic tips; Techart wing; Techart center radiator "smile" vent; Brembo GT Brake upgrade 380mm

 

Okay, but I'm not sure how front and rear pictures of your car address the question..

Congrats, nice car?

 

Thanks for the great info. I'll PM you more questions so we don't hijack the thread...
Looks good! Any side photos of the setup?