Looks like we're also still waiting on the National event schedule to come out, hoping for some cooler dates at Crows Landing like this year's Tour/Pro

 

The section widths are all in line and make sense; it's the tread widths which are funky. And reading up on how Tire Rack measures, they consider tread width to be the part of the tire which is in contact with the road; section width is the overall width of the tire.

Here's how they measure tread width: http://www.tirerack.com/tires/tirete...jsp?techid=201

And section width: http://www.tirerack.com/tires/tirete...jsp?techid=200

As measured on a 9" wheel, a 255/40/17 RE-71R has section width of 10.2" and tread width of 9.6."

As measured on a 9.5" wheel, a 265/35/18 RE-71R has section width of 10.7" and tread width of 9.5."

I know the rules haven't gone through yet but I'm tempted to get in touch with Tire Rack to ask some questions and verify their measurements. No matter what size tire we get, I'll need new wheels and want to know if I should be looking at 17" or 18" diameters. But yeah, I'm tempted to go 17" for lighter weight, better gearing, and lower cost. Part of my consideration is a very competitive Evo in ASP was running 275/35/17 Hoosiers for much the same reasons, while others were running the more "standard" 285/30/18.

As for unicorn sizes like 265/35/17, one of my buddies works for Maxxis and he claims to be the big proponent of the unicorn 245/40/15 they came out with for the VR-1. I put a bug in his ear about a 265/35/17 a size for the VR-1, though it still may not be the tire to have if the compound isn't competitive.

 

Just an FYI, the guy running 275s in ASP was Geoff Clark. Multi-time STU national champion, I think multiple triad winner, professional rally school instructor, and all around bad *** driver. The fact he did so well is more a testament to his driving cause he definitely didn't have a fully prepped ASP car. Its actually barely more than an STU car with hoosiers.

 

2016 PAX Numbers: http://solotime.info/pax/rtp2016.html

Spreadsheet comparing to 2015: https://docs.google.com/spreadsheets...gid=1298268609

STU fared better than the other ST classes.

 

Yep, talked to him a bit at Nationals this year but was being sneaky sneaky and maintaining anonymity, just cuz I never know who wants what info shared so broadly.

He is obviously better than most but other ASP'ers are no slouches either (IIRC, the top ASP drivers finished quite high in overall PAX at Nats) so I think the point still stands.

 

I'm not sure the same logic applies in STU. In ASP, all the top cars are Evos, so giving up 10mm per tire to get better gearing is a tradeoff that might be worth making. In STU, the top cars are Vettes/Z's that IIRC will be on 285's this year. If the course ends up sweepery you would be giving up more on 255's, IMHO.

 

Fair point. I don't have a firm stance or position on this and not trying to start a debate by any means, but I am trying to land on a basic direction for tire size and wheel size.

The 10mm per tire comes back to the funky tread width measurements I showed before where Tire Rack's current data shows the 265/35/18 actually has 0.1" less tread width in contact with the ground than the 255/40/17. So, based on those funky measurements, the 255 would still be a tiny tiny bit more effective in sweepers. I have a busy day but I'll try to email Tire Rack or PM the account on RRAX to get their thought on the measurements.

 

someone wanted to move evos to ssp? really?

http://cdn.growassets.net/user_files...k-December.pdf

 

I think if someone built a proper car, the evo would have big competition from the Saturn Redline hardtop (even if its an ultra rare three horned unicorn). It can make huge torque, fit big tires, has way better weight distribution, and SLA suspension f/r.

The 370z might also make a good contender on 315s. Under powered but much better balance also. I mean a CSP miata has no power but seems to somehow keep up with ASP at major events.

 

I mean... because they never have to slow down! I was just talking about it yesterday. 190whp, 1800lb, and 275 Hoosiers is gonna be fast any day. I really wish I hadn't passed on Tom Kubo's car when it was for sale. I was considering it, and it would have come with a full time codriver (Scott Fraser) as a part of the package deal

 

I agree that the tread width thing is worth hunting down - my comment was more of a general thing.

 

Keep in mind when hunting down tread width that a taller tire creates a larger contact patch given the same tread width.

 

Subscribed.
With the impending new tire allowances I may be looking for a car to put all my STU parts back onto.

 

Heard back from Tire Rack late yesterday and here's what they said:

"We had the tire tech team take another look. They found the 265/35-18 measured approx. 9.7" in treadwidth. Thanks for bringing this to our attention. Hope this helps!"

Looks like it's already been changed on the their site too.

 

I believe the 255/40-17 tread width is overstated on their site as well.