MatthewMiller

Tire Rack shows the 255 and 285 ExtremeContact Sport in stock right now. $161 and $206 each, for the two respective sizes.

vader86

In 17" yes, which is why I said "In a size for you"

car addict

Barrier

I have these on for a year I am pleased. The price was good, they are available in the staggered size I used.
The ride is good and they handle well for my street driven car here on South Shore of LINY. I cannot drive to the extremes here.
Barrier

krackenvette

Nitto G2 should be fine. The tires are much better than OEM C4 tires, I bet.
I have 11 years on my BFG KD's, and I am about to buy the G2's, as i have ZR1 size, and my options are limited.

krackenvette

Here are my 11 year old tires.

tdereggi

I recently put a pair of G2s on my rear (285), and my take is that they gripped extremely very well in dry and rain. There was Lots of rain the past few weeks to test it. I was not sold on their highway feel, where I felt a little bit of rough unevenness in the ride compared to my previous Michelins pilots or OEM GY Eagles. My plan is to move the 9.5" Rims and G2 to the front, and put G2 on new 11" rims in the rear. My goal is to obtain a low cost tire that can be daily driven, but still be an adequate improved AutoX tire setup. The bottom line is that if affordable tire is a concern the G2 is one of the few tires that have all sizes, such as 315 and 285 for 17" wheels. Anyone else run the G2s in autocross? ( I recognize there are a few higher recommended faster tires such as the Rival-S, or Hosier slicks, but they are either twice the price, or not street drivable, or not the full widths.).

MatthewMiller

Everything is relative when it comes to speed, right? And when you say "improved," the question is "improved compared to what?" So a G2 will get you around an autocross course safely and with some amount of speed. They won't be nearly as fast as a true 200tw competition DOT radial - we're talking about giving up at least 2 seconds on a typical 45-60second course. You'd be considerably faster on a set of Continental ExtremeContact Sports, which are still fully street drivable and are probably within a second of the Rival S and RE71R. I know they aren't available in the 315 size, but you'd still be a lot faster using four 9.5" wheels with 275s or 285s on them than you would with the G2 tires on the car.

But you also have boxed yourself in a bit on sizes. If you get 11" wheels and 315/35/17 rear tires, they will be about 1/2" shorter than the 285/40/17s you have now. So you're going to have taller tires on the front. That's not a major issue for performance, but it will look funny. You should have put 275/40/17 on your 9.5" wheels, because they would be the same diameter as the 315s. But frankly, if you were going to buy new wheels anyway I would have recommended that you just buy a full set of 18s in 9.5" or 11" widths all around and run the Rival S. Those are still fully streetable tires (they just don't last as long on tread wear) and they would be much faster for autocross work.

tdereggi

Thanks Mattheu. Im learning with all the different tire needs, I really need quite a few pairs of rims, so I'll probly just buy more sets of rims to do it right. When sticking with 9.5s, not a barrier cause used Vette rims at that size are cheap and available to obtain. Great point on the tire height. The plan was always to go 11" on all 4s (to avoid height and spacer issues) , I just haven't found 4 matching stock ZR1 wheels yet (that have proper offset for 85), while I had the cash on hand to get them. Not to easy to come by these days. Unless I give in and go with heavier after market Zr1 a-mold style, which are affordable. . Maybe I'll do that. But until then, not a big deal to rebuy the fronts in 275 . I can always dedicate my G2s for street, and do what you recommended, or just stay 9.5 on all 4s for now. decisions decisions. I was considering going 18 on new rim purchases for dedicated track wheels. But a little hesitant for dual use, because my long driveway is thick gravel, and concerned on the rims being more susceptable to damage from the rocks. The downgraded ride smoothness from 16 to 17 was significantly noticeable, but well worth it for performance. Have you run on 18s? How would you rate the 17" to 18" conversion regarding ride smoothness? Did you feel much of a difference on 18s?

krackenvette

There are some very good auto cross tires in 315s in 17 inch wheel size. Just saying.
I am at that point with my Vette, I am not buying anymore things to keep up with the Jones's. Its fricking fast already, way beyond my driving capability..

drcook

I am no longer on the fence. The set I had are gone. There is another member here on the forum that was saying he was having flat spot issues with the Nittos as well (IIRC). Maybe they got a bad batch of tires. The Coopers I have on now can set for days and not have any flat spotting.

MatthewMiller

I have a set of 18x11 Forgestar CF5 at all four corners for autocross use, running Rival S 315s. I can't compare it to a 17" size in the same tire (they don't make a 315 in 17"), so I can't be authoritative on ride quality. FWIW, I think those actually ride better than 315/35/17 Hoosier A7s or same-size Toyo 888 tires, both of which I also have on 17x11 wheels. So to me, the ride quality has more to do with the tire model (and maybe inflation pressures) than sidewall height.

If you can manage buying a set of dedicated(ish) 18x11 wheels for autocross use, that's really the way to go IMO. Then you can have really top-tier competition tires for that, and a nice street tire on the wheels you already have. For street use I just run my stock 8.5/9.5 sawblades with 245/45 and 275/40 tires (I was super cheap and bought Riken Raptors for them - all four cost less than one 315 Rival S!). You can get the Forgestar CF5 or F14 for about $1440 in my size, and I'm sure you can request a 32mm offset or close to it so no spacers would be needed. One thing to consider: you might want to think about 50mm offset plus 3/4" spacers. That way if you want to sell them you have a much bigger market of C4s and maybe even C5/6s that they would fit. It's always better to have wheels with too much offset than too little, because you can always use spacers. Another option for you might be four rear (18x10.5) C5 Z06 wheels. They'd need spacers too, but they are often cheaper than new Forgestars. There are repros, too: they are cheaper but heavier. So you have some options.

tdereggi

That's not to bad a price for the Forgestars, considering a custom size made wheel. Much better than the $3k+ that some others are. I love look of my Machined Sawblades, which is also what I run for daily driving, Originally I ran them without spacers, but recently bought a set of spacers for them. I thought about buying 50offst 11" to make it easier to change rim/tires back and forth without needing to also remove the spacers. But thinking that for compliance reasons and speed to repair things at the track, would be cleaner if I just get 11" wheels with the correct offset to not need the spacers. I'll probably end up dedicating the car for track use eventually anyways.

MatthewMiller

tdereggi, I forgot to mention one other option for dedicated 200tw autocross tires. You could buy 19x11 wheels in the offset of your choice and run the 305/30/19 Bridgestone RE71R. They are nearly as wide as the 315 Rival S, and basically equally fast. They are 0.6" taller than the Rival. I think this combo would be heavier than the Rival by 3-4lbs. A lot of people are running this combo in CAM-S and CAM-C this year, including a number of Vettes. From what I have seen, the choice comes down largely to feel: do you want a precise tire with good steering feedback but a narrower range of acceptable slip angles and a more abrupt loss of traction (RE71R), or do you want a more forgiving tire that likes bigger slip angles but doesn't have as much steering feedback (Rival S)? Also, consider that the C4 is a lot smaller than later Corvettes and pony cars, so it will look a little oddly proportioned with 19s.

But either tire is equally fast, and at this time these are the only two top choices. The Falken RT615K+ is also available in the 315/30/18 size. It's a step down in grip, but probably lasts longer. Everything else is at least one more step down from there.

What is a good autocross tire in 315/35/17 size? There aren't any that conform to 200tw. If you run a class that doesn't require 200tw or higher, then there Hoosier A7 (aka "purple crack") is the king of DOT autocross tires and it's available in that size. It is awesome, with more grip than the Rival S or RE71R and (IMO) nirvana-like handling traits. If I could run A7s legally in CAM-S, I would. I have been running a used set in a few NCCC events, and I am convinced that they were created by God himself and handed down to Moses on the mountain. But they are expensive and don't last as long as the 200tw tires, and they aren't realistically streetable (they have no real tread, so if it rains you're in trouble).

I don't understand the reasoning some people give about a grippier tire being "way beyond my driving ability." The more grip a tire has, the safer it is at any given speed. And for competition, if you aren't pushing the limits of your tires then you need to drive faster. It is really that simple. If you are trying to say that a beginner should build seat time on a cheaper and long-lasting set of less grippy tires, I can generally agree with that. But tdereggi was asking about tires that would have improved autocross performance over his previous tires. I did give him a lower-cost, multi-use option of the Continentals, which are still way better for autocrossing and the rain than a Nitto G2, and aren't too expensive (just not available in the 315 size). He of course gets to choose in the end.