Autocross Tires for C5
02-12-2012, 12:26 PM
#1
Racer
Thread Starter
Autocross Tires for C5
My current tires are street. They are Nitto NT05's all around (200 wear rating). 275/40-17's in the front and 295/35-18 in the rear. Wheels are 9.5" in the front and 10.5" in the rear.
I'm shopping for R compound. I'm already in SSM class, so switching to R compound doesn't move me to a different class as far as I'm aware.
Do you guys usually pay for the Heat Cycling?
I'm looking at buying 17"x9.5" front and 17"x11" rear wheels. Smaller diameter rear wheels should drop the un-spring weight a little and keep the tires out of the fenders. If I get these, I'd mount the same size tires I'm currently running in the front (275/40-17) but run 315/35-17 in the rear. I'm looking at Hankook Ventus Z214 C71, Kumho Ecsta V700 Victoracer, Kumho Ecsta V710 or maybe a combination of those. The cost of this wheel/tire set-up starts at about $1510 and goes up from there depending on tire brands.
If I did a square set-up, I can buy 17"x11" C4 ZR1 replica wheels from OE Wheel for $625 including shipping. 315/35-17 Kumho V700's run $1036 from Discount Tires Direct including shipping and heat cycling. Total would be $1661
I'm shopping for R compound. I'm already in SSM class, so switching to R compound doesn't move me to a different class as far as I'm aware.
Do you guys usually pay for the Heat Cycling?
I'm looking at buying 17"x9.5" front and 17"x11" rear wheels. Smaller diameter rear wheels should drop the un-spring weight a little and keep the tires out of the fenders. If I get these, I'd mount the same size tires I'm currently running in the front (275/40-17) but run 315/35-17 in the rear. I'm looking at Hankook Ventus Z214 C71, Kumho Ecsta V700 Victoracer, Kumho Ecsta V710 or maybe a combination of those. The cost of this wheel/tire set-up starts at about $1510 and goes up from there depending on tire brands.
If I did a square set-up, I can buy 17"x11" C4 ZR1 replica wheels from OE Wheel for $625 including shipping. 315/35-17 Kumho V700's run $1036 from Discount Tires Direct including shipping and heat cycling. Total would be $1661
Last edited by tb30570; 06-03-2012 at 05:42 PM.
02-12-2012, 01:42 PM
#2
Melting Slicks
Member Since: Jun 2002
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What have you done to the suspension?
Doesn't sound very good for autocross. The 335s will crack your rear fender lips and 275s aren't wide enough for the front...IMHO.
By using those rims you will push yourself out of stock autox classes and into SSP in SCCA events.
Doesn't sound very good for autocross. The 335s will crack your rear fender lips and 275s aren't wide enough for the front...IMHO.
By using those rims you will push yourself out of stock autox classes and into SSP in SCCA events.
02-12-2012, 02:14 PM
#3
Drifting
I'll agree with TedDBere's comments regarding the 335s on 19" x 12"s on the rear and that a wider tire than 275 would be the way to go up front.
Wanted to add that I've had excellent experience dealing with JW Motoring for the OEM C6 Z06 rims; bought two sets last year through them.
Wanted to add that I've had excellent experience dealing with JW Motoring for the OEM C6 Z06 rims; bought two sets last year through them.
02-12-2012, 03:29 PM
#4
Drifting
The "wildcard" is that you're planning on running C6 Z06 rims. The posts referenced, particularly from Solofast, are based upon C5 Z06 rims. 295s are no problems up front on C5 Z06 rims and probably shouldn't be an issue with the C6 Z06 rims, although they would be taller (and thus interference could be an issue).
Running a 19" x 12" on the rear would be taller and wider and hence could cause issues. On C5 Z06 rims, 315s are no problem and you could possibly even run 335s (I had 335 Escta V700s on the rear of my C5 Z - on the C5 Z rims - without interference issues (very slight rub against the brake ducts), although I wound up switching back to 315 V710s or A6s).
The most "popular" combo amongst the Super Stock C5 Z06 crowd are 295/315 A6s . . . but again that would be on C5 Z rims.
Running a 19" x 12" on the rear would be taller and wider and hence could cause issues. On C5 Z06 rims, 315s are no problem and you could possibly even run 335s (I had 335 Escta V700s on the rear of my C5 Z - on the C5 Z rims - without interference issues (very slight rub against the brake ducts), although I wound up switching back to 315 V710s or A6s).
The most "popular" combo amongst the Super Stock C5 Z06 crowd are 295/315 A6s . . . but again that would be on C5 Z rims.
02-12-2012, 05:19 PM
#5
Melting Slicks
Goodyears are notoriously stiff, and won't heat up as fast as as the Kumho's (which tend to be a bit more rubbery and will heat faster). That may not be a big deal since you are putting the Goodyears up front and the fronts heat up faster than the rears. It's just an issue that you will have to live with.
I don't know that mixing tires is a hot idea. I guess you could tune the car to work on each tire at each end, but you'd be on your own as far as setup goes. The other thing is that with tires of different construction (like V710's and Goodyears) can result in some strange transient handling. I'm not sure that I'd want the more rubbery tires on the back. If they were on the front you could live with it since it would just slow down the steering response, but stiffer tires on the front and rubbery tires on the back doesn't sound like a happy combination.
I don't know if these cars respond to bigger front tires all that well. We've tried the 295/17's and they didn't seem to be any better than the 275's. I think it may depend a lot on the specific tire. Remember that every tire, even though they look a lot alike is a very different tire in a different size. Even though it might be more tire and "should" work better, often times it just doesn't work out that way. Nobody would have thought that a 285/18 A6 squeezed onto a skinny rim on the Solstice would have just flat hooked up, but it did. For track days a square setup is common and helps not to overwork your front tires, but that's not a big deal in autocross.
The only way to know for sure is to try it and see how it works. Report back with your results so that we can learn from your mistakes..
I don't know that mixing tires is a hot idea. I guess you could tune the car to work on each tire at each end, but you'd be on your own as far as setup goes. The other thing is that with tires of different construction (like V710's and Goodyears) can result in some strange transient handling. I'm not sure that I'd want the more rubbery tires on the back. If they were on the front you could live with it since it would just slow down the steering response, but stiffer tires on the front and rubbery tires on the back doesn't sound like a happy combination.
I don't know if these cars respond to bigger front tires all that well. We've tried the 295/17's and they didn't seem to be any better than the 275's. I think it may depend a lot on the specific tire. Remember that every tire, even though they look a lot alike is a very different tire in a different size. Even though it might be more tire and "should" work better, often times it just doesn't work out that way. Nobody would have thought that a 285/18 A6 squeezed onto a skinny rim on the Solstice would have just flat hooked up, but it did. For track days a square setup is common and helps not to overwork your front tires, but that's not a big deal in autocross.
The only way to know for sure is to try it and see how it works. Report back with your results so that we can learn from your mistakes..
02-12-2012, 10:00 PM
#6
Melting Slicks
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It's not the diameter of the 335s it's the width. If you haven't changed the rear spring rate then the 335s will come up and hit the fender lip and crack it. They also wear the inside tub when cornering hard and will eventually wear through the tub.
295s on the front would work as long as the diameter isn't greater than an A6 295/17. Without a stiffer rear spring I wouldn't exceed a 315 on the rears. IMHO. But if you're drag racing then you'll probably want a soft rear spring so stay with the 315s.
295s on the front would work as long as the diameter isn't greater than an A6 295/17. Without a stiffer rear spring I wouldn't exceed a 315 on the rears. IMHO. But if you're drag racing then you'll probably want a soft rear spring so stay with the 315s.
02-13-2012, 04:49 AM
#7
I ran a set of the Goodyears last year (the new AC compound). What I found was somewhat contrary to what SoloFast says above. SoloFast, are you talking about the new compound or the older roadrace compound?
Anyway, what I found was,
1. Sidewall is actually pretty soft and not a great tire for the front of the car unless maybe it's a stiffly sprung car with wide wheels (relative to the tire width). A 9.5" front is not a wide wheel IMO.
2. The AC compound is very soft and overheats fairly easily. Upside is they work pretty good in cool weather.
All in all, there is no reason IMO to run the GY over the A6. They don't last any longer, cost any less or offer better performance.
Dave G.
Anyway, what I found was,
1. Sidewall is actually pretty soft and not a great tire for the front of the car unless maybe it's a stiffly sprung car with wide wheels (relative to the tire width). A 9.5" front is not a wide wheel IMO.
2. The AC compound is very soft and overheats fairly easily. Upside is they work pretty good in cool weather.
All in all, there is no reason IMO to run the GY over the A6. They don't last any longer, cost any less or offer better performance.
Dave G.
02-13-2012, 09:13 AM
#8
Melting Slicks
I ran a set of the Goodyears last year (the new AC compound). What I found was somewhat contrary to what SoloFast says above. SoloFast, are you talking about the new compound or the older roadrace compound?
Anyway, what I found was,
1. Sidewall is actually pretty soft and not a great tire for the front of the car unless maybe it's a stiffly sprung car with wide wheels (relative to the tire width). A 9.5" front is not a wide wheel IMO.
2. The AC compound is very soft and overheats fairly easily. Upside is they work pretty good in cool weather.
All in all, there is no reason IMO to run the GY over the A6. They don't last any longer, cost any less or offer better performance.
Dave G.
Anyway, what I found was,
1. Sidewall is actually pretty soft and not a great tire for the front of the car unless maybe it's a stiffly sprung car with wide wheels (relative to the tire width). A 9.5" front is not a wide wheel IMO.
2. The AC compound is very soft and overheats fairly easily. Upside is they work pretty good in cool weather.
All in all, there is no reason IMO to run the GY over the A6. They don't last any longer, cost any less or offer better performance.
Dave G.
I was talking about the older compound... Goodyears have, in the past always been a pretty stiff tire. That was their corporate approach. Every time we put GY's on a car and let Carrier drive it blind he could pick out the GY's... If they've softened them up that's interesting. Shows a willingness to try something different. Not that it worked, but if you don't try different things you don't learn.
I'd like to see G"y's back in the fray. Would you consider them as good or not quite as good as the A6's for autocross?
02-13-2012, 05:54 PM
#9
Dave,
I was talking about the older compound... Goodyears have, in the past always been a pretty stiff tire. That was their corporate approach. Every time we put GY's on a car and let Carrier drive it blind he could pick out the GY's... If they've softened them up that's interesting. Shows a willingness to try something different. Not that it worked, but if you don't try different things you don't learn.
I'd like to see G"y's back in the fray. Would you consider them as good or not quite as good as the A6's for autocross?
I was talking about the older compound... Goodyears have, in the past always been a pretty stiff tire. That was their corporate approach. Every time we put GY's on a car and let Carrier drive it blind he could pick out the GY's... If they've softened them up that's interesting. Shows a willingness to try something different. Not that it worked, but if you don't try different things you don't learn.
I'd like to see G"y's back in the fray. Would you consider them as good or not quite as good as the A6's for autocross?
IMO they're not as good as the A6. Although results were mixed. The guys that tested them (Thomason and McKee) both thought they were as fast or faster, but pretty much everyone else including myself found the opposite.
The compound is very soft. Picks up a lot more rocks and has more of the "glue" in them (sticky to the touch when they get hot). It really seemed like they should be a good tire, but I was not successful at all with them. I didn't do a back to back test, but I was getting waxed by people I normally do well against.
I think a couple of things contribute to the difference in results,
1) The slower turn in is a problem for Solo. I found the car needed to be quite a bit stiffer to make them work well for me in slaloms.
2) Last summer was particularly hot here in the middle part of the country. I think they overheated really easily. Despite them getting older, I was more successful on them in the fall when the weather got cooler.
This also explains why they would work for McKee in his SM2 car with wide wheels, stiff springs, and the more temperate west coast weather (and he tested in winter/early spring I think).
Dave G.
02-13-2012, 08:06 PM
#10
Melting Slicks
Dave,
Were the Gdy's better or worse on asphalt, as compared to better or worse on concrete?
Goodyears, in the past were better (compared to Hoosiers and BFG's before that) on asphalt and would literally chemically bond to seal coat surfaces. We used to jack up the car on goodyears on some seal coated surfaces and the car would suddenly unstick from the ground with a "pop" and jump an inch into the air... That's real chemical grip..
On concrete we would get our heads handed to us by the Hoosiers since they had a softer durometer and could get down into the concrete and develop more interactive grip.
I've also found that if the tire is too soft, the interactive grip falls off due to the rubber shredding, and the life goes to #3!! at the same time..
Were the Gdy's better or worse on asphalt, as compared to better or worse on concrete?
Goodyears, in the past were better (compared to Hoosiers and BFG's before that) on asphalt and would literally chemically bond to seal coat surfaces. We used to jack up the car on goodyears on some seal coated surfaces and the car would suddenly unstick from the ground with a "pop" and jump an inch into the air... That's real chemical grip..
On concrete we would get our heads handed to us by the Hoosiers since they had a softer durometer and could get down into the concrete and develop more interactive grip.
I've also found that if the tire is too soft, the interactive grip falls off due to the rubber shredding, and the life goes to #3!! at the same time..
02-13-2012, 09:04 PM
#12
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St. Jude Donor '08-'12, '14-'15
I'm looking at C6 Z06 wheels for my C5
front: 18x9.5
rear: 19x12
I'm also looking at 335/30-19 Kumho Ecsta V710 for the rear and 275/35-18 Goodyear Eagle RS DOT for the front.
The wheels and tires together will run about $1900 plus shipping.
Would that be a pretty good set-up for autocross and a little drag racing?
I've found a few sources for these wheels.
http://outboundlink.me/ib.php?DR_id=...%3Ft%3D2998780
http://www.oewheelsllc.com/Wheels_3/...-5272-Polished
http://shop.jwmotoring.com/product.s...&categoryId=20
front: 18x9.5
rear: 19x12
I'm also looking at 335/30-19 Kumho Ecsta V710 for the rear and 275/35-18 Goodyear Eagle RS DOT for the front.
The wheels and tires together will run about $1900 plus shipping.
Would that be a pretty good set-up for autocross and a little drag racing?
I've found a few sources for these wheels.
http://outboundlink.me/ib.php?DR_id=...%3Ft%3D2998780
http://www.oewheelsllc.com/Wheels_3/...-5272-Polished
http://shop.jwmotoring.com/product.s...&categoryId=20
http://forums.corvetteforum.com/auto...ing-wheel.html
02-14-2012, 11:29 AM
#13
Drifting
02-20-2012, 10:30 PM
#14
Pro
I run autocross about 3 times a year and drag racing about once a year. I don't want to spend a ton of money considering the frequency of use.
If running the same OD tires in front and rear is no big deal, I can get a set of C4 ZR1 wheels for about $570. The C4 ZR1 wheels are 17x11's and 17x9.5's. I should be able to pair those wheels up with 315/35-17's and 275/40-17's.
I'm looking at a few different types of tires. The least costly is the Nitto NT01's. The NT01's with wheels would run about $1330, but they are less sticky than other tires due to a UTQG of 100. They don't require shaving and I think I could drive them on the road if I really had to. The Toyo R888 is pretty similar but costs a little more.
The next cheapest are the Kumho V700 Victoracer which would run $1540 including wheels and shaving. These are softer tires with a UTQG of 50, but I'm not sure where I'd actually have the shaving done. I'm guessing I probably wouldn't want to drive these on the road very far.
For more money, I could go with pretty much a slick. I wouldn't have to have the tires shaved, but it would be pretty obvious they were not street tires on the road. The cheapest slick option would be a mis-matched set. If I put Hankook Z214 C71's on the front and Kumho V710's on the rear it would run about $1590 including wheels. The V710's are a little softer than the Z214's with a UTQG of 30 vs. 40. I'm not sure if different tire compounds is a good idea in autocross, although the front and rear sizes are not the same anyway so it's not like it's equal grip all around.
For even more money, I could get matching front and rear slicks with the BFGoodrich g-Force R1. These would run about $1670 with wheels.
There are a lot more options for even more money like a matching set of V710's, Goodyear RS DOT's or Hoosier A6's.
If running the same OD tires in front and rear is no big deal, I can get a set of C4 ZR1 wheels for about $570. The C4 ZR1 wheels are 17x11's and 17x9.5's. I should be able to pair those wheels up with 315/35-17's and 275/40-17's.
I'm looking at a few different types of tires. The least costly is the Nitto NT01's. The NT01's with wheels would run about $1330, but they are less sticky than other tires due to a UTQG of 100. They don't require shaving and I think I could drive them on the road if I really had to. The Toyo R888 is pretty similar but costs a little more.
The next cheapest are the Kumho V700 Victoracer which would run $1540 including wheels and shaving. These are softer tires with a UTQG of 50, but I'm not sure where I'd actually have the shaving done. I'm guessing I probably wouldn't want to drive these on the road very far.
For more money, I could go with pretty much a slick. I wouldn't have to have the tires shaved, but it would be pretty obvious they were not street tires on the road. The cheapest slick option would be a mis-matched set. If I put Hankook Z214 C71's on the front and Kumho V710's on the rear it would run about $1590 including wheels. The V710's are a little softer than the Z214's with a UTQG of 30 vs. 40. I'm not sure if different tire compounds is a good idea in autocross, although the front and rear sizes are not the same anyway so it's not like it's equal grip all around.
For even more money, I could get matching front and rear slicks with the BFGoodrich g-Force R1. These would run about $1670 with wheels.
There are a lot more options for even more money like a matching set of V710's, Goodyear RS DOT's or Hoosier A6's.
The Nitto NT-01 is a very good tire. The 888 is not and certainly doesn't work as well as it's predecessor, the RA-1 (which is not listed in Corvette sizes any more, at least not for C5 and C6s )
Be careful about buying Kumho Victoracers. Although they are great, I don't think Kumho has made them for 3 years and everything else is just old stock.
06-02-2012, 05:45 PM
#15
Pro
I am still new to this with my C5Z but I am using a square setup i.e same tires front and back. After 2 track days I have had no issues with all the nannies on, Competition mode on, or all the nannies off. I was prepared for all sorts of things happening but in actual fact, nothing happened. (Interestingly I did spin twice but both times it was driver error as much as anything. I do find that the car is not happy trail braking or at least I am not very good at it yet )
06-03-2012, 08:29 AM
#16
Burning Brakes
I run a square set up as well but unlike most I don't run the C5Z rims I run the C4 aftermarket ZR1 rims. That's 17x11 with IIRC 56 offset and 315 A6's. This is on a 99 FRC with stock suspension and stock ride height, I run with the nannies off all the time so I don't know if it would work with them on. I'm not saying that it's a better or worst set up then C5Z rims, I run them just because I already had them.
06-03-2012, 10:57 AM
#17
Racer
Thread Starter
I run a square set up as well but unlike most I don't run the C5Z rims I run the C4 aftermarket ZR1 rims. That's 17x11 with IIRC 56 offset and 315 A6's. This is on a 99 FRC with stock suspension and stock ride height, I run with the nannies off all the time so I don't know if it would work with them on. I'm not saying that it's a better or worst set up then C5Z rims, I run them just because I already had them.
http://forums.corvetteforum.com/auto...are-setup.html
Last edited by tb30570; 06-03-2012 at 11:04 AM.
06-06-2012, 09:33 AM
#20
Le Mans Master
