[JamesNoBrakes]

Because the system doesn't like numbers,

Thinking of 285/30 and 305/30. That gives exactly a 0.5" drop at both places (I know it doesn't always work out perfectly, but close enough).

Should be ok, technically allows the chassis to get closer to the ground than it would normally, but auto X is usually not a bottom-out/obstacle concern (except for the flexible ones!)?

Alternatively:

295/30 and 305/35 gives -0.39F and +0.1R, closer to square, a bit less sidewall support up front.

285/35 and 305/35 is the closest to stock diameter, +.06F and +0.1R, mostly "in the noise", but also if I don't have to carry around rubber further from the center of the wheel like the first setup, that's an advantage.

One of our racers does a C6 grand sport and he for sure has some smaller diameter tires on there, scraping the air-damn (but it's just plastic) at times.

Any issues with the first 2 setups and suggestions? Not DD tires, RE-71 types. It's my first foray into a dedicated race-wheel setup. Stock size, 19s (thanks DaveC113).

Thanks!

[DaveC113]

Hi, glad those wheels made it to AK!

Right now the best FS setup is probably 285/35/19 RE71RS all around. I switched to REs towards the end of the season, 295/35/18 on 18x12 square. Yes, they are stretched but this seems to work very well. I got some of my best results ever. 2nd overall at a PCA event, 5th at BMW, and won CAM and 12th overall at an SCCA ProSolo. The 12th overall is actually the most significant as SCCA is very competitive, I beat the 12th place finisher in CAMC at Solo Nats this year by just under 2 tenths.

I think Yok A052s are right up there but they cost more upfront and don't last nearly as long from what I can tell. The REs seem to be lasting for a lot of guys, staying fast without heat cycling out. My last set of Falken RT660s heat cycled out with half the tread left. I have 44 runs on my REs and they show more wear vs the Falkens, the rubber is softer, but if they stay consistent as they wear I consider that a big improvement. The REs also warm up super fast and don't fall off hard, so they are a lot less peaky vs the Falkens.

Also, the REs are the cheapest option for a competitive tire, both the 285/19s and 295/18s are about $389 each.

https://www.tirerack.com/tires/tires...RSXL&tab=Sizes

[JamesNoBrakes]

We don't have to worry "as much" about the heat. We have "generally" colder temps, but our pavement still heats up with so much direct sun and tires DO get "greasy" where they are no longer holding on as good as they should. So most are on RE71s and a few are on 660s.

Why not a 285 30 out back and 30 up front for the slight drop?

Thanks for the suggestions.

Post surgery, I'm making plans

[DaveC113]

GL with surgery!

I think the REs are only available in 35 series for 285/19s. It would be nice if Bridgestone expanded the sizes they are offered in, they could sell a ton of 315/30/18s.

[JamesNoBrakes]

Originally Posted by DaveC113

GL with surgery!

I think the REs are only available in 35 series for 285/19s. It would be nice if Bridgestone expanded the sizes they are offered in, they could sell a ton of 315/30/18s.

Ahh. That makes sense at least.

Also, I def wouldn't consider 295 on 12" stretched, that is pretty much exactly what you want for a stiff sidewall and still within the "4 sizes" that typically fit on any width wheel:

Screenshot of my tire size excel, highlighted column is 12" width:

[daniel.drives]

A fellow spreadsheet man, I likey

[Msquared]

First of all, thanks James for buying those wheels and preventing me from getting yet another set of wheels I don't really need (but man, they were tempting!). Probably saved me from a divorce.

As Dave alludes, your autocross tire sizes will be dictated by what's available in the type of tire you want. I fully agree with him that RE1RS and A052 are the only two options worth considering right now if you want the fastest tires, and that really constricts your choices. Ideally you would want 30 series to get the car and roll centers lower, but they aren't available in these tires right now. It's annoying. The Falken RT660 and Nankang CRS offer more appealing sizes, but they are a step behind in speed. I also fully agree about his assessment of the Bridgestone vs Yokohama lifespan.

The Bridgestone, much like the Yoks, is more than happy being stretched. The 285/35/19 on a 19x11 is absolutely not a problem. Truthfully, it's pinched on the front 19x10s, and I've even wondered about using their 275/35/19 up front instead. Not that it's an option for you, but the 295/35/18 is a beautiful fit on 18x12 wheels. These Bridgestones are wide for their nominal sizes: they are barely stretched at all on that wheel, and they perform great. I hypothesize that stretching the RE71RS helps avoid the "groove of doom" phenomenon that can develop at the lower pressures where it likes to run.

[JamesNoBrakes]

Originally Posted by daniel.drives

A fellow spreadsheet man, I likey

The highlighted blue are within like 0.25" within stock ride height, for purpose of winter-tire and rim selection. So I'm real close on my winter setup and spedo is correct.

[JamesNoBrakes]

Originally Posted by Msquared

First of all, thanks James for buying those wheels and preventing me from getting yet another set of wheels I don't really need (but man, they were tempting!). Probably saved me from a divorce....

Thanks. I think this all helps narrow it down. It looks like the RE71RS in 285 35 and the RT660 in 295 35 are the only real options then. I'm well aware it's better to be stretched fitting the narrowest tire on the widest rim (within mfr recommendations) for the sidewall support. Availability and other factors might dictate the exact one, but I feel these are the only two realistic options at this point. I don't know if these tires are better than the others...but I do know my AutoX buddies that bring separate AutoX wheels overwhelmingly use one of these two, and by the numbers most use the RE71RS.

Then I have to figure out getting the wheels there. I was considering a small trailer (I have a hitch ), but I think a carrier-rack on the hitch with two wheels on it and two inside might actually be the optimal setup. Most are within a 20 min drive to 45 min...but there's one that's around 2hrs that is fun too. Based on getting the wheels home (where I messed up and drove the wrong car that day), I'm pretty sure they won't fit inside with tires mounted.

[clyde]

Originally Posted by JamesNoBrakes

Thanks. I think this all helps narrow it down. It looks like the RE71RS in 285 35 and the RT660 in 295 35 are the only real options then. I'm well aware it's better to be stretched fitting the narrowest tire on the widest rim (within mfr recommendations) for the sidewall support. Availability and other factors might dictate the exact one, but I feel these are the only two realistic options at this point. I don't know if these tires are better than the others...but I do know my AutoX buddies that bring separate AutoX wheels overwhelmingly use one of these two, and by the numbers most use the RE71RS.

Beware overthinking. Probably better off choosing which compound you want and then picking a size that will work regardless of whether it's the optimal size. Also, if you weren't aware, Bridgestone expects to have a 19" 305 RE71RS in the spring. And if you don't have a compelling reason to buy something before January 1, you might want to wait until then to see what else might show up and if there's any more community clarity on what might be best or what the pros and cons of different compounds are.

Then I have to figure out getting the wheels there. I was considering a small trailer (I have a hitch ), but I think a carrier-rack on the hitch with two wheels on it and two inside might actually be the optimal setup. Most are within a 20 min drive to 45 min...but there's one that's around 2hrs that is fun too. Based on getting the wheels home (where I messed up and drove the wrong car that day), I'm pretty sure they won't fit inside with tires mounted.

Others have done that. Pics are from Bistrais' car at spring Nats this year. I wasn't a fan of how much motion it allowed.

You can fit all four inside the car, but it wouldn't be pleasant or allow much room for anything else. Two tires in the back seat, one in the passenger seat and one in the trunk.

About 19,000 miles on my 1LE are pulling a tire tire trailer. Makes life easier.

For events as close as you describe, I'd drive on my competition tires and if it rains for a transit, drive slower.

[DaveC113]

I converted an old bike rack. The load is within the specs for both hitch and rack.

It would be nice if Bridgestone offered some wider RE71RS sizes. It's been a popular tire so maybe they will...

Vitour has some tires that are apparently fast, but they're likely far off a 200tw and overheat quickly. They are sold by a guy who has been banned for cheating and has also made a business out of making parts that look like OEM but are not so others can cheat more easily. Personally, I'd stay far away from Vitour tires.