When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hey guys, need a little advice. Thinking of going to a square setup on my 2003 C5Z. I love the OE wheels so I'm thinking aboug running a set of rear 18x10.5's on all 4 corners with some R888's (305's because I hear 315's rub a bit). Car never sees the track but gets abused on the streets and canyon roads. I'm wondering what difference I will feel in this setup though? I want more grip overall, but I'm wondering where I will feel it mainly? Entry or exit? Sorry for the rookie question. Rapidly learning all the power in the world means nothing unless it can turn. So I'm looking to you guys/gals to set me straight and make this thing turn...
Hey guys, need a little advice. Thinking of going to a square setup on my 2003 C5Z. I love the OE wheels so I'm thinking aboug running a set of rear 18x10.5's on all 4 corners with some R888's (305's because I hear 315's rub a bit). Car never sees the track but gets abused on the streets and canyon roads. I'm wondering what difference I will feel in this setup though? I want more grip overall, but I'm wondering where I will feel it mainly? Entry or exit? Sorry for the rookie question. Rapidly learning all the power in the world means nothing unless it can turn. So I'm looking to you guys/gals to set me straight and make this thing turn...
Many forum members who track or autocross use this setup. I think you will enjoy it. Please post your results.
The car could go loose with higher front grip and speed through the turns. Adjust with air then suspension. To understand all of this I recommend the books Speed Secrets. You can get as dirty as you want on any race questions like this.
There are several ways you can go. The C5 with stock tires and wheels and a normal alignment is sensitive to trailing throttle over steer. That means if you let up in a curve the car will tighten into the turn (backend will feel loose and start to come around). Getting more tire width in the rear reduces that affect. On my C5Z I first went with 17x11 C4 GS offset ZR1 style wheels (you don't want the ZR1 offset since the wheels will stick out to far), the GS offset wheels will stick out about from a 1/4 to a 1/2 inch if I remember correctly. That setup with 315/35/17 Kumho V710s made the car a cornering beast. I had to be careful not to turn too tightly or the tires would rub my DRM brake ducts and the inside edge of the rims would touch the rear of the front lower control arms on tight parking lot type of turns. That would strip off any wheel weights that were along the inside edge. I really liked that setup and would have continued to run it the full time I had the car but the source of used tires dried up and I went to running 18x10.5 C5Z rear wheels on all 4 corners. With 305 Hoosier's installed the car never performed as well as it did with the other setup although the stock wheels were much lower in weight than the aftermarket GS knockoffs I had been running. Here are some pictures showing the 17x11 setup:
Depending on hard you are cornering if you run R888s you will have to run more negative camber or the outside edges of the tires will wear out on hard cornering. For track use I am running -2 to - 2.3 degrees negative camber. That is right on the outside limit permissible from the stock C5 camber adjustment cams. If your hard cornering is only occasional then you could probably get by with -1.3 or so.
Is he going to notice much of a positive difference on the street? One thing I think you will notice is the car will tend to hunt in the grooves in the road more - not an issue on track. That's a negative for street use IMO. To me and others that have commented on a square setup on track, it seems to make the car more neutral by adding front grip and reducing some of the factory understeer, plus the benefit of being able to rotate tires. Some have reported problems with AH/TC since the ratio of the tire diameters F to R is different, but I have not experienced that problem.
VERY interesting to read everyone's opinions and different views on this. One thing to know/consider is this car will not see the track, but gets flogged on mtn and canyon roads. 9/10 and 10/10 efforts to the point of brake fade (OE setup for now, LG cooling ducts and SS lines on the way for now). the groove thing is honestly already TERRIBLE so what is a little worse right? lol but its only on a few specific spots around the house that I just dive out of the grooves and its fine.
One thing that will drive me insane though is getting a CEL or warning about the AH/TC. I'm starting to wonder if I'd be better off with just running the widest R888's I can on the stock setup? I would like more front end grip but I do a lot of left foot braking so I can easily get into trouble. I would rather a car oversteer than understeer any day of the week.
What if I ran a 315 rear and a 295 front on square wheels? Would that help the AH/TC to not flip out? With the R888's I'm banking on a set of tires every 5k miles or so anyways not too concerned with tire rotating.
If I didnt live in WA state (gotta love the unpredictable rain) I would almost run slicks on the street...
I'm starting to wonder if I'd be better off with just running the widest R888's I can on the stock setup?
I'm starting to wonder why you think it's safe to be pushing your car so hard on public roads.
The ACTUAL limits for a C5Z are WAAAAAAAAAAY above what even an experienced driver should be doing on the street. No matter if it's the stock tires or R888's.
Why aren't you doing this on a track or even autocross course?
I'm starting to wonder why you think it's safe to be pushing your car so hard on public roads.
The ACTUAL limits for a C5Z are WAAAAAAAAAAY above what even an experienced driver should be doing on the street. No matter if it's the stock tires or R888's.
Why aren't you doing this on a track or even autocross course?
Jeremy Foley
Yeah, this ^^^^. I can't fathom driving the car on the street like I do at an autox... then again, maybe the OP's 10/10th's is actually 6/10ths of what the car can actually do?
As far as R888's, they're probably one of my least favorite tires in all of creation. For street driving (even h00ning), get a decent set of street tires (PSS, Conti DW, Rival-S, RE11, RE71, RS3, etc) and call it a day. What's another 0.1-0.2G of grip when you're not competing?
Thanks for your quick replies, but most times 10/10's is the road or me. Now and again it's the car, but usually because I made a mistake or crap conditions.
What's your reason for not liking r888's? And for me I do want every ounce of grip I can have out of a tire because it's a safety net, I'm not out to put myself or the car, I'm out to have fun and sometimes limits get pushed. If I know I can go around a corner at 60, and that's the limits of grip but feels nice and fun, then I will continue to do 60. So I want a set of tires that will allow 65-70 so I have built in buffer if that makes sense.
I drive an hour or two into the middle of nowhere have my fun and come home. It's one thing to wreck my car and myself on a telephone pole, it's a complete other to hurt someone else. We need to assume a certain level of accountability in eachother guys. Stupid people weed themselves out quick...
Yeah, this ^^^^. I can't fathom driving the car on the street like I do at an autox... then again, maybe the OP's 10/10th's is actually 6/10ths of what the car can actually do?
As far as R888's, they're probably one of my least favorite tires in all of creation. For street driving (even h00ning), get a decent set of street tires (PSS, Conti DW, Rival-S, RE11, RE71, RS3, etc) and call it a day. What's another 0.1-0.2G of grip when you're not competing?
Not a big fan of 888 either... But I used to get them cheap for many years so I ran them on the track and street...
This year I am on the Hankook TD (hard)... So far no complaints! Definitely worth looking into if you want leave them on for street and track.
I'm starting to wonder why you think it's safe to be pushing your car so hard on public roads.
The ACTUAL limits for a C5Z are WAAAAAAAAAAY above what even an experienced driver should be doing on the street. No matter if it's the stock tires or R888's.
Why aren't you doing this on a track or even autocross course?
Jeremy Foley
I absolutely concur! The limits of the stock C5 Z06 are way too high to be approached on the street. If you doubt that, please go to a track event and ask an instructor there to show you HIS limits in YOUR car. The C5 Z06 is a TRACK car which can be successfully driven on the street, and still have civilized creature comforts like stereo and A/C.
Some like me have not had trouble with AH/TC. I can't pinpoint why that is. That said, I turn off nannies on track at this point. Not sure I'd suggest that for you at 10/10ths on the street.
Ok will do, I'm going to swap over to C6Z shocks and T1 sway bars soon so after the height and stance is determined then I will look into having an alignment done...
Thanks for your quick replies, but most times 10/10's is the road or me. Now and again it's the car, but usually because I made a mistake or crap conditions.
What's your reason for not liking r888's? And for me I do want every ounce of grip I can have out of a tire because it's a safety net, I'm not out to put myself or the car, I'm out to have fun and sometimes limits get pushed. If I know I can go around a corner at 60, and that's the limits of grip but feels nice and fun, then I will continue to do 60. So I want a set of tires that will allow 65-70 so I have built in buffer if that makes sense.
I drive an hour or two into the middle of nowhere have my fun and come home. It's one thing to wreck my car and myself on a telephone pole, it's a complete other to hurt someone else. We need to assume a certain level of accountability in eachother guys. Stupid people weed themselves out quick...
So when you say 10/10ths; you're referring to 100% of your ability, not 100% of the car's potential? Same thing with the tire "safety net" you describe... you can do 60, the tires/car can do 70?
As for the R888, I haven't found them to be "enough" better than the top-end street tires available to offset their significantly faster wear/heat cycling and on-road manners (horrible tram-lining). Other folk's opinions may (and probably will) differ.
Originally Posted by nskyline34
NT01's? Thoughts?
The NT01 is a better tire than the R888 though I still don't know why you're stuck on using the second tier R-comps when street tires are perilously close to their performance, offer better wear, and have better street manners.
The wider front wheels is a great mod for these cars. Easy way to eliminate the stock oversteer, better turn-in, ability to rotate tires around the car, etc.
Originally Posted by Xian
The NT01 is a better tire than the R888 though I still don't know why you're stuck on using the second tier R-comps when street tires are perilously close to their performance, offer better wear, and have better street manners.
Agreed. From someone who used R-comps for years, I just made the switch to Michelin PSS and am really impressed with their abilities (dry traction, wet traction, highway cruising, and on-track driving).
05-26-2015, 11:20 AM
Wider Front Wheel/Tire Effects
I absolutely concur! The limits of the stock C5 Z06 are way too high to be approached on the street. If you doubt that, please go to a track event and ask an instructor there to show you HIS limits in YOUR car. The C5 Z06 is a TRACK car which can be successfully driven on the street, and still have civilized creature comforts like stereo and A/C.
