4BW tire/wheel sizing for Track

[PL69]

Hey all,

Anyone knows if 275/35-18 + 295/35-18 are doable on the appropriate custom wheels on the 4BW ?

Is there enaugh wheel well clearance ? I know 285 square is doable (John Heinricy did it in is campaign car per someone on the forum who talked to him: https://www.motorsportsnews.net/2023/06/05/racer-and-engineer-john-heinricys-latest-challenge-is-an-scca-national-championship-in-a-cadillac-ct4-v-blackwing ) but Ive been trough this route before on my BMW and didnt like how the car felt and would prefer staggered fitment, he is also probably doing it to prolonged tire life for the races wich I don't need to do.

I ordered a 2024 for track duty and want to start looking into the optimal setup, I have 3 track days on a 2023 as of now and really feel like the chassis and suspension can take it, even a JB4 with a mild map (70-80hp more) I feel could be nice.

Feel free to chime in

 

[poor-sha]

John was trying several sizes, but I know he started with a 285/295 setup, I believe it was 285/30-18 and 295/30-18. He mentioned though that they had some rubbing and was experimenting with spacers as well as the different size combos. We talked about the fact that the ABS doesn't behave quite right with a square setup, and if you're running things like AH and PTM it could affect that as well.

 

[poor-sha]

I decided to dig in to a few options in both slicks and some bigger DOT legal tires.

 

[PL69]

I was looking at tire choices and found something interesting, Goodyear Supercar3R are available in 265/275 sizes. These would be even better than any 200TW tire in 275/295 whatever.

This would reduce the OEM 7mm rake to 3.5mm, I don't think this would screw up the aero since just weight in the car could have more effect than that and it's still better than removing it completely with a square setup.

poor-sha thanks for your input, I guess if they tried with 30's and still got rubbing there is mostly no chances bigger 35 will work. In many articles about the Blackwings they specifically talk about how the tires are maxed out and they even made the tire without rim guard on the inside to maximize space (even trough I find the mention about this pretty ridiculous since who is going to hit a curb on the inside..)

 

[poor-sha]

I was looking at tire choices and found something interesting, Goodyear Supercar3R are available in 265/275 sizes. These would be even better than any 200TW tire in 275/295 whatever.

This would reduce the OEM 7mm rake to 3.5mm, I don't think this would screw up the aero since just weight in the car could have more effect than that and it's still better than removing it completely with a square setup.

poor-sha thanks for your input, I guess if they tried with 30's and still got rubbing there is mostly no chances bigger 35 will work. In many articles about the Blackwings they specifically talk about how the tires are maxed out and they even made the tire without rim guard on the inside to maximize space (even trough I find the mention about this pretty ridiculous since who is going to hit a curb on the inside..)

I really like the 3R, so that looks like a great option. There are also a number of ways to get some solid discounts on them which makes them cheap to run (e.g. USAA). I'm not so much worried about the rake and aero, rather it's the issues that the taller fronts will throw off the wheel speed sensors.

The car will think the fronts are travelling slower than the rears, that means under braking it might put more bias to the rear, or PTM will intervene sooner thinking there is wheelspin. Realistically, I doubt the car is that sensitive, or that us mere mortals will notice the difference.

Here is an updated chart:

 

[DriveOn]

I'm making similar plans. Right now I think my wheels will be
18x9.5+22
18x10.5+45
That gives me 275s upfront maybe even 305s in the rear but at least 295s. I also wanted to run the F1Supercar 3R but their 18 inch sizes are fairly limited. I'm currently running proxy R888R on my stock rims and I've become accustomed to those tires, so maybe I'll go with them again, 100 TW

 

[PL69]

I'm making similar plans. Right now I think my wheels will be
18x9.5+22
18x10.5+45
That gives me 275s upfront maybe even 305s in the rear but at least 295s. I also wanted to run the F1Supercar 3R but their 18 inch sizes are fairly limited. I'm currently running proxy R888R on my stock rims and I've become accustomed to those tires, so maybe I'll go with them again, 100 TW

R888R don't hold a candle to newer tires like RE71RS, Nankang CRS, Trofeo R or Supercar3R

I've read on Rennlist that ppl are 1-2sec faster on CRS vs NT01 or AR1. Technology is moving on.

I just find it weird to have to upgrade to 19inch to be able to run larger tires but I guess we have to work with the parameters of the platform.

 

[Mike Martz]

R888R don't hold a candle to newer tires like RE71RS, Nankang CRS, Trofeo R or Supercar3R

I've read on Rennlist that ppl are 1-2sec faster on CRS vs NT01 or AR1. Technology is moving on.

I just find it weird to have to upgrade to 19inch to be able to run larger tires but I guess we have to work with the parameters of the platform.

I am looking at running SCCA time trials S1 class and that requires 200tw tires any suggestions in 5BW sizes?

 

[PL69]

I am looking at running SCCA time trials S1 class and that requires 200tw tires any suggestions in 5BW sizes?

If you need to stay in 200TW

Nankang CR-S (2023 compound) is available in OEM 275/35 305/30 sizes and is the absolute best tire right now. Second choice would be Azenis RT660

If you want to trade speed/grip for durability I'd recommend Hankook RS4 Wich should last a lot longer vs the above tires.

 

[Mike Martz]

If you need to stay in 200TW

Nankang CR-S (2023 compound) is available in OEM 275/35 305/30 sizes and is the absolute best tire right now. Second choice would be Azenis RT660

If you want to trade speed/grip for durability I'd recommend Hankook RS4 Wich should last a lot longer vs the above tires.

Thanks!