George33

I'm tracking a C6Z with R7 Hoosiers on oem 5-spoke Z06 wheels with oem tire sizes:
18x9.5 front and 19x12 rear
275/35/18 and 325/30/19

Can I do better by going to wider front and rear tires ?
I'm already invested in 3 sets of C6Z oem wheels, so going to another wheel size is not an option.

Note: front is -3.25 camber and rear is -1.50.

So, I can feel the beating coming (LOL) but I have to ask, since I've read thread after thread but haven't found a definitive answer. . . What's the widest tires you can run on the C6 Z06 FRONT & BACK (using the stock C6 Z06 rims) without rubbing or dash error messages ??

Or, should I just stay with stock sizes?

Thanks

ApexWheels

Hoosiers run wide to begin with, so while you could squeeze 295/30-18 up front and 345/30-19 out back, I'm not sure it would be any faster for you. Sidewalls will be very pinched and feel/feedback will be pretty poor in comparison to your current setup. I'd also be surprised if the tread width on the ground changes much between the two setups.

If you want more performance, you're going to have to upgrade from the factory wheels.

George33

Thanks for the post. I've heard conflicting stories, but you never know from who they are coming from or what experience they have.
The street guys... that's one thing. For the track... that is different.
Your explanation makes sense, plus upsizing the front tire in an R7 changes the profile from a 35 series down to a 30.

ApexWheels

The change in aspect ratio is fine in most cases as it's based on the first number. 275/35-18 is essentially the same height as a 315/30-18. But 295/30-18 is a few tenths shorter in overall diameter.

srshaw3

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I also have 3 sets of stock wheels, and now keep track.tires on 2 sets with the 3rd having MPSS for rainy days. I review the sizes of the tires vs. just looking at the aspect ratio. I have a spreadsheet that include most of the ones I considered, Toyos, Goodyear, Hoosier, Michelin, etc.

I am usually on 275-295 fronts and I think always 325 rears.

George33

At 325/30/19 . . . the rears have never been a problem for me as far as grip is concerned.
They give me a lot of confidence in the corners and just enough slide to rotate the car and trail brake when needed.

But I could use a bit less push and more threshold braking from the fronts using the 275's.

srshaw3

Do you have adjustable sway bars? Plenty of suspension tuning there if/when you do.

My gut feel is I can usually reduce the push/understeer with the throttle, sometimes with less but also sometimes with more as the rear will give more slip angle.
I am in my first year with a splitter on this car, too much time getting it right, but anticipate this will help as well. I went with a wing last year.

I still run stock calipers and rotors, although the calipers were refreshed with SS pistons.

George33

I am also on stock brakes, but just ordered a StopTech BBK which I should be getting in about 60-days or so.
I considered a front splitter, then ordered one, but then reconsidered and sent it back.
I didn't want to upset the balance of the car without a rear spoiler, since I'm not ready to do that yet.
Yet.

George33

So where do you like your tire pressures with Hoosier tires coming in hot?

C6_Racer_X

I can share some long experience with Hoosier R7 and earlier versions of their DOT race tires back as far as R4s (both personal experience, and experience of other's who have used Hoosiers on their cars that I've driven or closely observed). They run the best lap times (and give you the most grip) when the wheel you mount them on is about a half inch narrower than the tread width given in the Hoosier catalog. Mounting a wider Hoosier R compound tire on a narrower wheel doesn't seem to improve lap times, but the tires wear out much quicker. I would not ever recommend going on a wheel that's a full inch or more narrower than the tread for a Hoosier R compound DOT tire.

You're golden on the rears, and the fronts you're using are actually a bit wide for your wheels (maybe). I definitely would not go any wider. There might be a misprint in the current catalog, though. It's showing the tread width on the 285 as wider than the 295. I don't think that's correct.

pierrel

So your saying my 345/30/19 is more than I should have on my stock 5 spoke C6Z06 rims? I have a set of 275/35/18 for the fronts. None of the tires have been mounted yet, but been on the shelf for about a year waiting for this darn pandemic to end and track days to open...
I'm also interested Im suitable tire pressures, like OP.
thanks!

srshaw3

I have only run one set of Hoosiers and may have been too low on the front as I wore the outside corners off quickly with 3+' camber. With almost all the tires I have used @34 hot seems good.