Just met John today with my new black CCW's (pics soon) 18x10 & 18x11.5 with 275/335 Michelin Pilot Sports. I have a few questions...

1. What PSI should I run the tires at for good wear on the street...?
2. The car feels very loose at speed, and has a vibration above 80
3. The car was just alligned to factory specs-but are they all out of whack now with the larger tires...?
(I torqued all of them properly in stages also)

 

TTT :D

 

Dave,

I would start out at 30psi cold and see where you end up. I find that they perform the best around 34 psi. Some of the correct pressure is decided by the ride that you like. I wouldn't go less then 30 and more them 36.

If you have a vibration at 80.......drive faster! No... it sounds like a wheel out of balance.

I also have 18's all the way around and it definately changes the feel of the car. I had my alignment changed to the 02 ZO6 spec and made a huge difference.

Post pictures when you can!

 

I have zero problems with mine and have been over a 150 mph. I pump up the PSI on the track..check the tire max pressure on the sidewall. I think on the Michelins 335's it is 52, I put my cold pressure at 45. It makes for a harder ride, but this is the PSI the tire was designed for and allows for proper wear. If you feel like you are sliding everywhere..a couple of things...I would check your toe in and toe out. Also if you were used to your old run craps and these are brand new tires..give them a couple of 100 miles to wear in...new rubber always feels a little different until it breaks in. The vibration could be wheel out of balance or as I mentioned previously toe in and out.

 

I ran my CCW Big Street package at 36 PSI.

vetterdstr :cheers:

 

[QUOTE]..check the tire max pressure on the sidewall. I think on the Michelins 335's it is 52, I put my cold pressure at 45. It makes for a harder ride, but this is the PSI the tire was designed for and allows for proper wear. [QUOTE]

Tires are universal, so the max rating is not necessarily the best. The max pressure rating is for the max load and I'm sure you're Corvette is not running the maximum load. Too much pressure and you'll wear the middle of the tire, contact patch is not optimum and you loose the flexibility of the tire which hurts your launch. Too little and you'll wear the outsides and increase the flexing which builds heat and degrades the tire. Start somewhere around the mid thirties and adjust from there. :thumbs:


[Modified by 87GN&98VET, 5:15 PM 2/17/2003]

 

I drove a friends C5 with big rubber and his car seemed to "hunt the grooves" on public roads MUCH more than my stock tires. Maybe this is just a characteristic of grippier tires?

 

Thanks for the advice :thumbs:

I had the front two rebalanced (were off quite a bit-now the car can be driven easily at speed) and will have the backs rebalanced, and a four wheel reallignment to Z06 Specs :cool:

Yes, it wanders a bit more, and the shocks feel like they've lost some "jounce" possibly due to them being "base" shocks now with heavier rims & tires on them-or no longer riding on rockhard RF's. It doesn't feel like it is prone to bottoming out, but the ride is so supple now-I feel like I need firmer shocks!!

Also, I think it takes at least two days+ for the suspension to settle-especially after being in the air for two weeks.

Finally, I lowered the PSI from 37-40psi to cold 33 in the front, 32 in the rear. As the temps in HELL :reddevil -oh, I mean South Florida go up so will my cold PSI (1-2 psi) in the next month.

I figure run 1lb less on the rears to wear the edges of the 335 on the 11.5, even though the sidewal is not bulging (in fact it matchs the Goodyear sidewall profile).


Check more pics out: http://forums.corvetteforum.com/zerothread?id=494715


[Modified by MiamiDave, 3:56 PM 2/17/2003]

 

Your pictures aren't working.

 

F!@k!! :cuss

Let me roll up 'me sleeves and get to work here...

 

Dave--I'm running about 32 to 33 as well and I have never had a problem, I have the vinci/penski 16pt adj drag shocks and keep them pretty firm and this probably makes a lot of diff, my car feels like its nailed to the ground at all speeds, I also had 18" front wheels before the CCW package and maybe I was already adj to 18" frt wheels and didn't notice as you might. Glad to hear you found a balance and alignment situation. When I bolted mine on at Johns I never had to do a thing I'm surprised they needed balancing. good luck Bill

 

87GN you are correct in your statements..I should have been more specific these are the tire pressures that John (CCW) had recommended to me for the track...if you drive agressively the outside of the tire gets as worn as the middle. For normal street I drive at 38 psi....

To the dude with the comment that the larger meats on his friends car tended to hunt for grooves...a wider contact patch will do that..but even more will an aggressive alignment the more negative camber and toe in the more the core is going to hunt. I would recommend going to Vette Brakes & Products (VBP) website and looking at their online catalog..page 6..for some base line alignment specs for street, autocross, and track...it gives brief explanations for all 3 setups..once again they are just base line and I believe have a lot to do with what tires you are running too.

I will tell you right now that when you are making over 400 rwhp you want less camber in your rear...when you put a lot of negative camber in your rear for the street,,,,the car will ride mainly on the inside of the tire...causing this to wear first..and no matter how many offramps and hispeed corners you take on the street..it will not simulate track conditions and heat cycling that takes place when running on the track..thes are just some suggestions..stay around zero to -.25 (-1/4neg) camber in the rear and -.25 to -.50 (-1/4, -1/2) in the front on the street and you will get fairly good tire ware, the car will not hunt for grooves as much (track the road), and will give you enough contact patch to hook up...these are just my experiences with talking to other people and on my own car. Good Luck.

 

It will seem like it wants to follow any ruts in the road. The wider front tires are doing that. My C4 has wider fronts that my C5 and it will follow the ruts like it's on rails (the negative camber I run doesn't help either). As far as the feel of your shocks... that's probably due to not having the stiff sidewall of the runflats anymore. You might want to check with John. I'm sure his wheels are lighter than your stock wheels.

Anyway, enjoy them. They look great. :thumbs: