>What tire pressures are you guys running? I've heard of a huge range...for the street I run 36 front/ 34 rear...but I've heard anything from 30-36. I also run 40 front for autocross and track days.....Thanks

 

245/45/17 tires and 35psi on all of them....

 

have p245 50R16 i run 35psi on all 4.

 

I just run what the door placard on my IROC calls for, 30, IIRC.

JamesC

 

I have been running 31psi. I just had my BF Goodrich Comp T/A rotated at the shop I bought them from who suggested 35 psi.

 

depends on temps another tool to throw in the tool box
http://store.summitracing.com/partdetail.asp?autofilter=1∂=PHP%2D01005&N=700+4294853823+115&autoview=sku

 

Yea...I'm seeing what I suspected 30-35psi range....that's alot: a 5 psi swing! Are all of you guys experiencing normal tire wear? I didn't know GM called for 30? That just seems low to me. For sure it would renforce the understeer these cars have!

 

I run 40 front & 28-30 rear (cold) on 275/40-17's

More air in the rear makes it get loose when I really hammer the turns. Any less it feels unstable.

The high pressure in the front helps with tire wear as the wide tires tend to burn the edges off.

I daily drive it this way with fully worked suspension. It rides like a truck, but handles excellent.

The only way to know what your car likes is to experiment. I would start around 35F 30R & start tweaking. Unless one routinely pushes the car to the point of sliding it through a turn, you may never notice a difference of a few pounds pressure.

 

Thanks, Lonnie....yea, I've noticed a lot more scuffing of the outside edges of the front tires. I first thought it was an alignment problem, but I have the camber plates all the way inboard! Must be the way I like to keep the gas on while doing wide sweeping turns at speed!

 

i run 36 upfront and around 30-31 out back

 

Mine are 44 alll around

 

^Dang. Going for mpg?

Mine are all 35 +/- 1. My gauge isn't that great....

 

well i have 52 psi max tires.
my theory is that they have thinner side walls.
my fronts are 40-42 rears are 35.
too oversteery with more rear pressure.

 

max psi is 35 for my tires.
I run 30-31 in summer conditions. 34-35 in winter, but I don't drive in winter either way so...

 

40 all around, 225/50/ZR16.. It's like driving a bar of soap...

 

Dude! Any abnormal tire wear at 40psi? That's high....stock suspension?

 

This really depends on the tire. My answer will shock you.

I ran Goodyear GS-D3's on the car for just over 2 years with 24,000 miles total life. They are a 51 psi max tire. I ran "warm" temps of 49 front and 46 rear and had perfect wear.

I have had numerous sets of BFG's on this car (Comp T/A's, KDW), I have ran Firestone SZ50's and SZ50EP's which most were 44 psi max tires some were 36max psi tires. Most of those 44 max psi tires I ran aprox 38 front 34-36 rear range based on which brand andits charateristic. The EP's were higher though I recall using 40 in the fronts and around 37 in the rears.

Dean

ps- general rule of thumb, usually the lower the profile and the wider the tire, the lower the pressure.
My bi plias racing skins on my supertruck I run aporx 15psi lefts and 25psi rights(Cold) after 40 laps they will come in aporx .4 larger in diameter adn aprox 19psi lefts, and aprox .8-1.0 larger diameter and 31-35 rights. Anything over 36 general will start to blister on me.and really cause havoc on the suspension settings based on whether its the RF or RR.

 

Vetruck,
That pressure was on a 3rd gen? I'm surprised you could go that high in the rear without making it very loose. May I ask your spring/bar setup?

I tried more rear pressure & spent a lot of time watching the road from the side windows. Removed some rear bar, have rear shocks full soft & it still turns better with less pressure. Did this with Nittos, KDW & Goodyears.... maybe I could with a sticky race tire.

 

the factory recommended pressure is only good on stock size and grip tires with a stock suspension. once you start changing stuff it becomes more or less useless. besides, every thirdgen made probably said 30 psi or whatever, this does not account for the vastly varying weights, suspension setups, and power of the many different models available, let alone the differing tire sizes they came with...

 

It was a radically built V6 car with great weight bias/ I could run much stiffer in the rear then the V8 cars. THe only thing this car did not have on it was a cage. I built it to be our grocery getter. Seriously. It was the closest thing I could call our family car. Every car I own is built. Rear springs were progressive rate building to 225lbs and the rear bar was a solid 25mm. There is more to it, but thats the basic. It also utlized shaft mounted bumpstops that were progressive rate and set to the desired ride height to actually make contact.

 

That's a high spring rate for the rears, Vertruck! Roads must be good where you drive! I'm in NYC so the potholes would destroy my ride if I had such high rates on. When you hammer on a turn, does any small bump just cause the whole rear to slide?....mine does and I'm riding on stock springs with 34psi tires!

 

No, Its progressive. No linear rear springs. They build to 225 when set hard into compression. This car has low polar weight, low sprung weight via use of very exotic parts. It does not dribble across the road on bumps, the suspension actually functions.

here's a website on that car I did a few years ago:

http://www.cardomain.com/ride/518752

 

To explain a little further, its like spinning in circles with your arms outstreatched compared to spinning in circles with your arms tucked to your sides. Tucked to your sides you can change directions quicker due to less polar inertia.

Well, suspension parts have weight when they travel up and down. The less they weight the faster they regain road contact AND AND AND the less they jar upward and unsettle the chassis of the car unsettling it and causing loss of traction also. Weight is major unsprung weight ratio is major, polar wight can be major but also can go too light to make a car unstable and twitchy (I have a ways to go before that were to happen.)

Here is a shot of the cars rear. The exhaust removed and reworked with the I-pipe muffler and then just small addons to tune the sound made for a 40lb drop in the rear of the car. Thats a carbon fiber driveshaft under there weighing under 5lbs, drilled flangle axles, lightweight ring & pinion gear sets, larger but lighter 4pot disc brakes w/ drilled and sloted 12.2 SRP rotors, Alum diff cover, arp studs (heavier) but with titanium lugnuts (very small and very light- thank you T. Cnningham).... there was alot of stuff I did to this car. Check out the brake build I did for the front. Huge brakes and very lightweight.

 

I want your car Dean.
I ran low 40s in the fronts, and upper 30s on the rears. Going to back down to upper 30s front and mid 30s rear due to more tread ware on the center of the tire. BFGoodrich g-Force Sports 275/40ZR17s

 

I have BFG G-Force KDW tires on all 4 in a 245/50/16 size. On the street I run 32 front and 30 rear. When I autocross, I run 38-39 front and 30-32 rear depending on the weather conditions and current shock settings.

 

BFG 265/ 50r16 at 37 psi

front tires run at 40

 

At VIR (Virginia International Raceway) I run 30 psi in the front and 28 psi in the rear. No sliding at all in the turns.