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Tires?

4K views 16 replies 6 participants last post by  PaganEgyptian 
#1 ·
Okay guys I've got most of my suspension set up besides tires. I'm going with some revalved Bilsteins (if any one knows of someone that does this please notify me) or Konis. For swaybars I'm going with the 37mm Hotchkis. Now for the Tires. Im going with 275s all the way around at first. If I visit the track frequently and have traction problems I'm gonna step up to 315s all the way around. Okay I'm in between BFGoodrich KDs and the Eagle GS-D3s. What would you guys suggest and what do you run, and whats your feeling on those tires?
 
#3 ·
My cars gonna be more of a road course car. Im not a big fan of cars that only go fast in a straight line, then the imports just go hide in the twisties.
 
#5 ·
1970judge said:
315's is still way to big. try a 245,275 setup.
I dont think 315s are to big. I've personally driven a 245/245 set up Conclusion: not enough grip, A 245/275 setup: understeered more than I'd like, a 275/275 setup very well balanced, but not enough traction for high horsepower cars on the street, even spun like crazy out of a few slow corners. 275/295 Didn't like at all. 275/315 Great grip every where but understeered like crazy 315/315s Insane grip and very well balanced. I may also look into a 295/315 setup.
 
#6 ·
IMO 315's in front is waaaaay too big. The largest I'd go in front would be 285. For you the GS-D3's would be great. But IIRC they don't make a 285. BFG does make a 285 KD series (kd, kdw, kdws) though. I have the 285 KDWS's right now. I switched to those from 275 F1's.
 
#7 ·
I'd personally go 275/315 GSD3s with that 37mm front bar you're talking about and see how you like it. If it understeers too much for your liking, add a bigger rear bar (bigger rear sway bars dial in more oversteer). For that 37mm front bar, I'd imagine you'd want something along the lines of a 23mm rear bar to balance it out.

Sam Strano revalves Bilsteins for any specific application. www.stranoparts.com and he also has 35mm hollow front sway bars, which I would recommend unless you're dead set on the 37mm front bar. Call Sam and tell him what your goals are. He'll talk your ear of laying out the best possible options to meet those goals. Really a very helpful guy who could give you more advice and info in a 30 minute phone converstion than most of us could hope to forget in a year or research poking around the internet.
 
#8 ·
Doesnt a car understeer because the front tires loose traction before the rears? And dont bigger sway bars help traction? If it understeered and I put a bigger bar in the back, It would just make the back stick better, and in turn, the car would unsteer more. Sorry if im wrong this is just the way its always been explained to me.
 
#10 ·
Exactly. Tires do have alot to do with it, but body roll and spring stiffness also plays a factor in how much under/oversteer you get. Bigger front bars make the front stiffer, but more prone to push once tires lose traction. Whichever side you add a bigger bar to, you're going to get less body roll. That means less energy is wasted in body roll, and more energy is transmitted to the tires, and tires can only do so much (even if you are running 315s up front). This is why I and many others feel that 35mm solid is about as big as you need to go up front, and most prefer a 35mm hollow bar.

Tires are almost always going to be your limiting factor, but which tires lose grip (front for understeer, rear for oversteer) and how the car behaves once that grip is lost is a product of the rest of the suspension setup. More meat helps, but it isnt the answer for a poorly setup suspension. A 35mm hollow front bar, a good set of revalved Bilsteins from Strano coupled with your springs of choice (whether stock or aftermarket) will get you started and is a tried and true foundation. After that, just adjust rear bar size up if you feel the car is understeering too much.

FWIW: My car has had quite a few setups under it, and right now I dont even have my front bar connected for drag racing purposes, but I normally run a 32mm/19mm bar combo with Koni SAs dialed up about 60% in the front and 10% in the rear, all on stock springs with 275 Kumho 712s all around. It's a good all around setup thats main goal is good street manners that can also work decent at the drag strip and autocross course, with very little understeer/oversteer bias (enough of a balance that on the streets I cant tell which way it falls, and I haven't autocrossed with this setup yet to be sure, but I think the car has just a touch of understeer, which it should, as the gas pedal can balance that out in short order), but I trade off and take more body roll for a bit more comfy ride and that kind of balance.
 
#11 ·
I really don't mind a hard riding daily driver. I actually prefer it. My best friend has the prokit and the 37mm front sway bar. He hates it on the road, says its to rough, but I like it. I think it makes the car feel very buttoned down and tight. So ride quality really isn't a huge concern for me, mostly performance. Roads are quite good out here anyways.
 
#12 · (Edited)
The sway bars wont have any impact on how the car rides. Springs have a little to do with it, but if you get a shock that can properly dampen a 600# spring the ride wont be that harsh at all (it will be a sporty ride, but not overly rough). What shocks is your friend running with his ProKit? I had the ProKit and regular Bilstein HD (non-revalves) and the ride wasn't the best in the world (regular Bilstein HD shocks barely have enough dampening for the factory spring rates).

If you like a stiff ride, and you're as picky as you seem to be about how you want the car to handle, bite the bullet and drop some serious money into your suspension. Koni SAs with Ground Control coilovers and spring rates that suite your needs (going to be pretty high in your case, I'd guess around 550-600# front springs and maybe as high as 200# rear springs). That coupled with a 35mm hollow bar up front and a 21mm rear bar should be a night and day difference and be what you're looking for (Strano can help you get the spring rates just right for your needs).

For myself, I've got the Koni SAs already. I'm going to work with the bars and step up to a 35mm hollow bar and a 21mm bar soon. Then I'll add the Ground Control coilovers and custom springs at a later date (I'm going for something a little different though, so I'll probably go with some 400-450# springs up front and some 150# rear springs).
 
#13 ·
if the car doesn't see rain, u could check out the Nitto 555R(i think thats the Road race version). if you want a good place to find out about RR setups, check out www.FRRAX.com (f-body road race and auto x)
 
#15 ·
After doing some more tire research im between the GS-D3, BFG KDs, and the Nitto 555. Not Rs. I need at least a 200 Treadwear, a 300 would be nice but I think I could swing 200.
 
#16 ·
FWIW, one manufacturer's tread wear cannot be directly compared to another's treadwear, as they go through different standards. Treadwear is only helpful is deciding between different tires from the same manufacturer (a little tidbit I picked up from a guy I know who works in the tire biz). So if the 555R has a treadwear or 180, and is known to get about 15,000 miles, you better look for something in the 300 range if you're looking at regular 555s if you want around 30,000 miles out of them.

30,000 miles on stock shocks, and with a ProKit on it. That car has to ride like utter crap. An underdampened car will also handle much worse than a properly dampened car. People spend tons of money on springs, sway bars, subframe connectors, etc and neglect the most critical piece of the suspension as far as ride and handling go, the shocks. If you're on lowering springs, go revalved Bilsteins at the least. Stock height can get away with off-the-shelf Bilstein HDs. If you want adjustability, Koni SAs are the way to go. And if you're into drag racing, some QA1s are the ticket.
 
#17 ·
Take a Look at Firestones new Wide Oval. I run 285/40R17 BFG KDWS up front, good for general driving but I would rather have Firestones by the feed back I read on Tire Rack. I run Sumitomo HTR35Z 315/35R17's out back. -Tim
 
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