Softer compound or larger contact patch?

**QShip** · #1 (**permalink**) 01-21-2008, 01:08 AM

I'm interested to hear what people would prefer for track use: our stock wheels with Pilot Sport Cups or larger width wheels with wider PS2s?

Here are the details on the two configs:

PSCs on 235/40-18 and 265/35-18, or
PS2s on 265/35-18 and 295/35-18

If I could find the right size Cups for the larger wheels, there would be no debate.

Jim Michaels · #2 (**permalink**) 01-21-2008, 02:51 AM

I'd bet on the Cups/OEM wheels for lower lap times, but it might be close when the PS2s got worn down some (or if shaved new). According to Tire Rack, the PS2s would cost $168 more, and weigh 16# more (unless shaved). One can get 9 and 10" forged wheels weighing around 19 or 20#, so that would save some weight compared to the OEM wheels.

To fit 265s on the front, you'd need at least 9" rims. Do you think you can use that much tire in front without rubbing anywhere? There are also some other brand R-comp tires in 245 and 275 sizes that have diameters that will work.

**QShip** · #3 (**permalink**) 01-21-2008, 03:24 AM

I've been eyeing that RAC Monolite group buy for the 9" and 10" wide rims. I read a bunch of those posts as well as the threads on r compounds, and I've been trying to figure out what are the widest tires I could run on them without causing inducing understeer (hence the 265/295 combo, although you bring up a good point about potential rubbing), as well as the widest DOT-approved r compounds that would work.

If a 265 width is too wide for the front, I'd likely decrease the width of the 295 rears as well to keep them 30 apart.

From all I've read, it seems like I should just turn my stock 18s into track wheels with DOT-approved R compounds and just use the RACs for the street.

What wider DOT-approved R compounds would work on a 9"/10" rim set?

Jim Michaels · #4 (**permalink**) 01-21-2008, 04:48 PM

Hoosier R6 (245/40 and 275/35) and Kumho V710 (245/35 and 285/30). Although both of those are DOT approved, they shouldn't be driven on the road, as to and from events. They're much like slicks.

Yoko A048s come in the same sizes as the Michelin Cups (235/40 and 265/35).

Look at Toyo Proxes RA-1, and the new R888. Also the BFG gForce R1.

Also in the 245/40 and 275/35 sizes are Falken Azenis RT-615 and Nitto NT-01.

Search for a thread where CC members have reported what wheels and tires they are running. I think all of the tires I mentioned are mentioned in that thread.

**Krokodil** · #5 (**permalink**) 01-21-2008, 06:45 PM

If limited to your presented options, then stock wheels with PSC.

In my experience the PS2 will quickly come apart on the track. While they are sticky when relatively cold (which is partly why they are a great street tires), they do not like to get hot.

After a couple of track days the outside edges of the fronts will begin to delaminate and "chunk" in rather large sections leaving exposed cord. I went through two sets rather quickly. I may have a tendency to overdrive the tires, but others have also had he same problem.

Lots of folks about have mentioned the leading track tires (may want to add the Nitto NT-01 to he list), but the leading street tire is probably the Bridgestone RE01R.

Size is certainly the problem. With no mfg making a stock size r-compound the options are limited. Staying as close to stock as possible is preferable, so you may wish to consider the NT-01 in 275/40-18 R and 245/40-18.

Also, if you are just getting started on the track (I have know way of knowing), then you may want to consider the OEM Bridgestone RE050. These can be had for less than the PS2 and work much better on the track. They provide better turn in, are more consistent as they get hot and wear quite a bit longer than the PS2 (probably twice as ling).

Cheers,

**jim@tirerack** · #6 (**permalink**) 01-21-2008, 08:33 PM

Even though the PS2 is a good performance tire they will not be as good on the track as a track tire. The reasons listed above are all correct. The PSC will also withstand the abuse much better than the PS2.
If I can help let me know.

skelly · #7 (**permalink**) 01-21-2008, 09:18 PM

Saying that ps2's will chunk at the track may give those considering a track day the wrong idea, i.e. that they are inevitably going to experience that problem. My experience is that there are drivers out there drving their ps2's at the tires' limits without that failure. Maybe its driving style, camber, inflation presure, etc.

**Krokodil** · #8 (**permalink**) 01-21-2008, 10:06 PM

Quote:

Originally Posted by skelly

Saying that ps2's will chunk at the track may give those considering a track day the wrong idea, i.e. that they are inevitably going to experience that problem. My experience is that there are drivers out there drving their ps2's at the tires' limits without that failure. Maybe its driving style, camber, inflation presure, etc.

I agree that style, camber, pressure, etc. will certainly influence wear rates.

An average driver running the occasional DE at a moderate pace is not likely to see significant damage in just a few events. My experience, however, is that as the driver increases in pace they will overheat and delaminate the PS2 (assuming stock camber).

My assumptions in rendering the above opinion is that this is a driver new to the track environment, with stock camber settings (even at factory max), who is interested in more than the occasional event (he is interested in track-specific tires as well).

As I stated in my original post, I have a tendency to overdrive stock tires (and stock camber) trying to keep pace with others running a different spec. I only offer the caution so that the OP does not run out and drop $1400 on new PS2s and then get upset when they seriously degrade after a few events.

I run the PS2 on the street and it is an excellent tire (although I like the RE050 better), I just do not think it is a very good track tire. If you look back through my old posts you will see that this was not my original opinion on the tire, but my wallet has convinced me otherwise.

Cheers,

rlm328 · #9 (**permalink**) 01-21-2008, 10:29 PM

I am running Nitto NT-01 245's in front and 275's in back. These are an R compound tire, and they have exceedingly good grip. Just remember the bigger the tire the more power you need to accelerate it, so tire size and low end torque go hand in hand. And the Cayman does not have an over abundance of low end torque.

If you are going to be tracking your car and want to put the softer compund tires on your car you will need to get a track alignment or you will eat up the outside edge of any tire you put on it. Have fun.

**QShip** · #10 (**permalink**) 01-21-2008, 10:58 PM

Thanks for the feedback, guys. I think I'll go with the Cups on the stock rims for the track.

BGLeduc · #11 (**permalink**) 01-21-2008, 11:08 PM

Quote:

Originally Posted by jim@tirerack

Even though the PS2 is a good performance tire they will not be as good on the track as a track tire. The reasons listed above are all correct. The PSC will also withstand the abuse much better than the PS2.
If I can help let me know.

Yes, you can help....

Use the Tire Rack's considerable influence to get some of the tire makers to create some decent R Comps in stocks sizes for the Cayman S and Boxster S!

Heck, I would even settle for some of the hot SCCA ST tires (tread wear 140 or higher) in the correct sizes for the Croc.

Cheers,

Brian