Hey Ben, great seeing you guys the last couple of weeks.

Brian has run STU before. At recent practices I've had Ken run my car for multiple runs (and Tom Berry I think on the same day), and couldn't get within a sec of Brian on a high grip surface. Brian is an elite driver for sure, and w/proparts they're getting the most out of the car. But people have to give Geoff credit. I've driven with him, and in his current Evo, he doesn't give up anything to any other drivers.

We need to look at the front corner grip vs tire size. The front heavy Evo would need to run 340mm front tires to equal the same wt/tire width as the 350Z on 285s! Even if both cars were on equal width tires, the 350Z can run much wider rims, effectively increasing the contact patch. IF the Evos and STis can even fit 285s, it will be on severely pinched wheel widths.

 

Brian in the Z w/ 285s?







Interesting, what's the spring/unsprung corner weights of an STU Z? With Tasha in the car we're at about 1000lbs per side (f).

 

I used 53/47 for the 350Z, and 60/40 for the Evo, both @ 3100lbs. So I think it worked out to 775 for the 350Z, and 950 for the evo, off the top of my head. I think I'm over 950 too. As with most cars, a lot of the wt reduction comes off the rear; exhaust, spare tire, jack, etc.

With the C5 vette coming in too (with 50/50 balance, and lower CG), now would be a good time to eliminate the AWD tire size and diff handicap, and just let all the cars run a simple and common rule set.

 

Yep, 2WD's got 265s, the RX8 went to STX, and nationals switched to concrete, all in one year. Not ideal for assessing the impact of each change separately. Thankfully it's a little easier to do that this year.

 

fwiw, we're at 61/39 with Tasha and 1/4 of a tank of gas, 3177lbs.

 

At '13 Nats when he was in STR on 255's I beat him by 1.8 seconds. Now on 285's he's beating me by over a second and a half.....its so amazing how many people overlook the tires and physics and just think its all driver....what am I, choped liver?

 

30mm of tire isn't getting anybody 3 seconds, and clearly you're not chopped liver.

How did nobody manage to build a successful E46 M3 with 285s?

 

That was just one event, though. Don't forget this event from last season as well:


There's a lot of course dependency going on here as well, unfortunately. If a course has a lot of steady-state, there's just no way a car with 245s and a 61:39 weight split is going to keep up with a 53:47 car on 285s.

 

Don't forget about the 11" wheels, and in total its actually 120mm more
M3 couldn't fit 'em without pullin rear fenders, 265's iirc where widest without a pull.

 

Just to be clear; everyone is aware that Brian P. is an exceptional driver.

The discussion is about the AWD STU tire restriction rules that don’t appear to be making sense with the addition of the 350Z and C5…because, I see the same thing happening with a STU prep Corvette with a good driver.

285s on 11” wheels … that seems unfair
What are the actual tire sizes? Is the 350Z running 285/30 18? I don’t think that any MY Evo could fit those with an 11” wheel anyway.

 

245 vs 285 doesn't sound like a huge difference. After all, 40mm is only about 1.6 inches. But when you look at 245s next to 285s the difference looks pretty substantial:


(From here http://www.s2ki.com/s2000/topic/9961...about-w-i-d-e/ )


(From here http://g35driver.com/forums/20-inch/...-evo-k110.html )


(From here http://ls1tech.com/forums/wheels-tir...-question.html )

 

Agreed. Peters is an incredible driver and deserves a lot of credit for his driving skill.

But the real issue is that the turbo AWD cars are heavily handicapped in STU relative to the 350Z and C5. If you read through last year's STU thread, you can see the ridiculous power graph that was (supposedly) used to justify putting a 245-equipped Evo in the same class as a 285-equipped 350Z. The graph had some unreasonable power numbers for an STU-tuned Evo and made it look like the Evo was in a different league in terms of power. Hence the 245-width restriction for the turbo AWD cars and 285s for the balanced 2WD sports cars.

 

I disagree…but you could run 205s to prove your point.

About the E46 M3s if they don’t break on the way to the event, I don’t think that they can fit 285s following the STU fender rules.

 

The E36 M3 could only fit about a 255, but I'm pretty sure some people tried the E46 with 285s back when the tire allowance was first changed. I don't think anybody stuck with it more than a year. There was a long thread on bimmerforums about it STU E46s, but most of it is accusing people of boost cheating and complaining about how the E36 doesn't stand a chance. Then it died around the time an E36 won nationals, weird. :P

 

The E46 is too heavy. Which is why people gave up on it. They are a blast to drive in STU trim though. I'll admit, I was shocked the SCCA moved the Z in the 1st place. Especially after in STR trim, it was faster than STU. I'm also shocked by how much Brian has been winning. Course dependencies aside. That car and he are FAST!

I've felt that the tire limitations were odd in ST. And felt it should be more like SP. If you can fit it, you can run it. No wheel or tire limits.