180 treadwear tires at a 200 treadwear Auto-x?

[Dr G]

I am planning a new suspension build around wider wheels and tires. I have three tire sizes in mind: 305/30-19 (or 305/35-19) which I know will fit. 315/30-19 which I'm pretty confident will fit, and 325/30-19 which will most likely fit, but might get a bit tight. (this is on the front which is my limiting case)

Problem - the first and last sizes I listed are available in 200 treadwear. But the middle size, which is my preference, is only available in 180 treadwear (Michelin Pilot Sport Cup 2).

Question - if I opt for the 180's and then want to enter a Goodguys auto-x for example, will I be allowed to run at all? In some type of catch all class for people who don't fit any of the standard classes? Or will I be denied entry?

I'm not sure how the rules work, which is why I ask. I am not particularly interested in fitting into a class, as long as I can run.

Thanks.

[Flash68]

Thinking that would be just exhibition at that point but I may not be up to speed on the latest and greatest from Goodguys.

[Dr G]

Originally Posted by Flash68

Thinking that would be just exhibition at that point but I may not be up to speed on the latest and greatest from Goodguys.

Thanks Flash. Some research yielded this from the Goodguys website, though for 2016:



Most of my auto-crosses are with the BMW Club and POC. They don't care about treadwear ratings. There are few GoodGuys events near LA, so this is an outlier condition.

[rustomatic]

They'll still give you a time. It seems that treadwear ratings these days, especially with the USCA and Lemons/ChumpCar stuff, are somewhat based on sales and event sponsorship (ask Tire Rack), rather than actual tire compound. In other words, many of the 200-level tires would have been rated at much lower numbers a few years ago. My old Hankook RS3s (very popular in Lemons racing) were 200, but everyone says they should have been 140. The Nitto NT05s I just got look ridiculous, especially with that whole treadwear indicator thing . . .

Build what suits you.

[dontlifttoshift]

The RS3s were 140tw and then were upped to 200tw when seemingly every race series (chump, lemons, USCA, GG, SCCA street classes) went to 200 as their spec number. It's marketing for sure, as the RS3s wore better than the then current crop of 140tw tires, aside from the Star Specs.

Heard from a guy whos cousins boyfriends uncle works with someone who lives next door to a guy that works at michelin that the Cup2 could easily be a 200tw tire but they don't care to play in that space. That's why they have the Rival.

To the OP, I would be willing to bet that RE71s in 305 would be faster than the Cup2s in a 315 on your typical autocross course......and especially at Goodguys where time between runs can be significant.

[Panteracer]

I ran at the Goodguys recently this year with 200 rated Rival s tires out
back and Hankook dot road race tires in front (the Re71re rivals I had were hitting
the fenders so I changed them so I could run).... They gave me a time
before I broke the car... In the past I have run dot road race tires
all around and they showed my position but no time

As others have said the Rival s.. they now have a rival s 1.5, Bridgestone re71re
(I think is the best) but things change as Falken now has a new tire rated
200 are the ones playing with the numbers to make the tires work for the class

I have run dot road race tires at 40 rated with 200 rated tires
in the front and back and back and front and cannot tell the difference
on an autocross track... Drove that way to the good guys event in
the rain... then that is a different story

Bob