Well long term goal (maybe years from now) is to RR my 95 Z28. So I want to plan out upgrades and only do things once. Getting on a road course means I would feel better having a better brake setup. I'm currently running LS1 fronts and stock rears. Brake motive rotors and unknown pads. Using stock Camaro 10 spokes with kumho V710's 275/40/17.

I'm on the fence whether to go to 18x10.5 in order to find used slicks easier than 17's and also able to run CTS-V calipers. Or switch to a 17x11 square setup and maybe run a base C6 brake package (someone one here is running this setup).

It seems like finding some 18x10.5 speedlines are the wheel of choice, but finding a square set used seems hard. Same goes for 17x11 square set. Maybe buying 2 staggered sets and then sell the remaining wheels is what needs to happen?

I keep hearing the following:
1) 18" take offs (used a couple of times) are easier to find than 17's
2) Because of #1, new 17's are cheaper than new 18's
3) Brake package plays into wheel choice (c6 or Brembo having different dimensions)

Anyone that has been down this road I would appreciate some input.

I'm weighing out tire availability/cost and brake package possible scenario.

 

i am running 18x10.5s all around with a 295/35 tire (nitto nt05's). i would say go with the 18's because of the more plentiful tire choices and you will have the option to run the brembos if you ever want to upgrade the brakes. also, and this is personal prefereance, i like the shorter sidewall tire that comes with an 18" rim.

edit: forgot to mention i am doing the same thing as you, setting up my car for autocross/roadrace sometime in the near future. i currently have the stock lt brakes on it, but have complete front/rear ls brakes sitting in my shed (waiting on current rotors/pads to wear out) and will be doing the c5 upgrade up front, and eventually if i feel like i need it would like to go brembos (ctsv or 5th gen)

 

I haven't auto'xed in years and never been on an open track even for an HPDE, but I've sort of built my daily driver with that in mind. I've been sticking with the 17's because I don't need a larger rotor or better calipers for my purpose. If I did then I'd probably go with OEM C5 Z06 18x10.5 wheels if I could find them, only because they are light and cheap compared with something like an Weld RT-S.

18's are more expensive but also offer more choices, both in new tires and take-off slicks. Maybe decide on how much rotor & caliper you need first, then wrap it with the necessary tire & wheel?

 

I'm dealing with this right now and you've pointed out each of the items I'm struggling with.

First, if you're looking at HPDE, you would be surprised how far an aggressive pad on the stock LS1 brakes will carry you. I'm running R-comps and my tires are the limitation on my brakes. My track pad mix is a Hawk DTC-60 on the front and HP+ on the rear.

As for tires, it's been easier to find scrubs to fit the 18" x 10.5" wheels. I started by buying a staggered setup of OEM C5 Z06 speedlines. I prefer a square setup, however the staggered set still feels good to me as long as I adjust the other factors properly to account for the car being more prone to understeer. I don't have any problem with fitment of the staggered setup as I'm still running the LS1 brakes (as noted above).

As for the brakes, I will eventually upgrade to either the C6 kit or the CTS-V Brembos. I'm leaning towards the Brembos and if I went that direction, I'd just pick up another pair of the 18 x 10.5" Speedlines. Plenty of these pop up for sale at the Corvette Forum, so it usually isn't too tough to buy the pair you need. Interestingly enough, there's still a market that exists for the 17 x 9 C5 Z06 front wheels, so you wouldn't have too much trouble moving those.

Here's my $.02 after taking all into consideration: I think the 18 x 10.5 square setup is the way to go. Square setup. Easy to find tires. Will accomodate the Brembos if you go that direction later.

 

I myself will probably be going with the 17 setup as the most tire I can fit anyway in the front is a 275. Would love to find some front c5z wheels but most seem to sell them as a staggered set (understandable) so I would have to buy 2 sets to make my set then sell the other 4 as a square 10.5" wide setup. Meh.

 

Fwiw, I've been running 17x9 wheels with 275 40 17s and C6 13.4" front brakes. The car is otherwise well sorted out, doing 2:40 laps at Road America and 1:13 laps at Joliet Autobahn north circuit.

I would actually base my choice of wheel around tire availability and aesthetics. The smaller (and perhaps less attractive) wheel/tire combos can work perfectly well if you're happy with them. In general, they are lighter and the tires they use are also lighter, which makes your suspension react to road changes more quickly. BUT 18s apparently have greater tire selection and there are lightweight options too. Just don't assume that bigger = better.

Miatas prove that one wrong every day

 

Thanks guys.

I can't speak to the fact if the LS1 brakes would suffice during RR as I have never been there. But it seems anyone I know that has a Camaro on a course has gone the CTS-V direction.

It seems to make sense to go with the 18x10.5, maybe run a more aggressive/properly selected LS1 pad+rotor combo and see how far that gets me. Then I'd have ability to go to the C6 or Brembo package.

 

What wheels are you running and still using base C6 brakes? I know Boss002 said he is running 17x11 CCW classics with C6 brakes.

While bigger isn't always better, a Miata running a 255 or 265/xx/15 is like us running a 315 lol. I believe 15x9 or 15x10 is very popular in the Miata crowd.

EDIT: Well correct me if I'm wrong but base C6 calipers are not THAT much better than base C5 or even Fbody LS1 brakes? I read C6 calipers have more support ribs to reduce spreading under heavy braking and getting pad taper when compared to C5 calipers. I won't bother upgrading my LS1 brakes to C5 since C5's are't much of an improvement. Jumping to the CTSV caliper seems to be a different ballgame.

 

+1 for 18s.

 

*17 x 12 CCW's , I also have a center section to run 13" wide if you really want to go crazy. I've also ran 275 Hoosiers on a miata before and that's literally just holding the throttle and steering.

I can't say i've currently noticed any difference from the sidewall on the 17 vs 18, but I do know I kept the 18's to run popular 200 TW tires for the Optima Ultimate Street Car Challenge and to play in the CAM Challenge. As for USED Tires, i've ran so many free 315/35/17's I can't count, but to each area there is a different market.

 

I probably should have given more detail. The 13.4" Z51 rotors are a step up from base size (12.7, I think), but not as big as Z06 (14"). From my completely unscientific research, the Z51s are the largest rotors a muscle car era hot rodder can stick in a 17" wheel without grinding. My particular set happen to be paired with massive Wilwood 6 pots. Wilwood makes calipers that are a specific drop-in replacement for Z51 corvettes and they are stupid expensive. I got lucky and someone else paid for mine.

2nd gens have a different wheel offset than 4th gens and corvettes, so I had to use 2" spacers. With that in mind, 4th gen Corvette 17" Sawblades and 4th gen Camaro SS 17" wheels fit fine. It looks tight in this pic, but there is actually about 3/8" space between the rotor and the wheel. Because of the wheel design, 4th gen guys would have to stick with the base corvette rotor size. And yes, I agree the CTSV front calipers would be much better than stock. There is no benefit with going to bigger calipers in back. I have stock 4th gen LS1 brakes on my back axle.



Miatas are... well, Miatas. Putting a LS-anything in one is one of my dreams

 

OE wheels seems to be viable option getting some 18x10.5 C5 deep dish wheels then pick up some tires later. This should allow the CTSV setup (I will double check they fit). Not the lightest, but for my "wanna be" competitive nature it will allow me to knock "to -do's" off my list and get the car ready.

And Boss002, you are right. It must be areas, because not too many people around me are running 17's, and if they are it is not a 315 wide tire. It's about even with cars being either a Corvette (using 18's) or Miata (using 15's). Then you have a couple of Evo's tossed in the mix. And then there is me.

 

I went 18's and never looked back. If you still want those 17x11 lemme know.

 

There are 18 inch wheels on my car, and 4 sets of 17's in my basement. That should tell you something. The 17 inch tire selection is poop.

Go and register on corvette forum. Don't look for a whole set of 18x10.5. Find pairs, or singles of speedlines. Buying one or two at a time also helps keep your costs manageable. Those OE wheels replicas will be HEAVY compared to an actual OEM z06 wheel.