Pressures and Alignments for V710s

[Dave Barker]

So guys, it appears that I will be running V710s next year in Solosprint competition as compared to my trusty old Victoracers. I have a heavy car ,3680 lb with me in it, and used to use -2.5 camber and cold pressures of about 35 front and 30 rear which climbed about 7-9 lb during competition. Tire size is 275/40-17 on 9.5 " rims.

From a few people in the USA I am hearing that the V710 needs less camber and lower pressure on a similar wgt car. Any experience?

For those of you not familiar with Solosprint (formerly Solo 1), tires should be run at road race specs and not Autox, as they certainly get to operating temperatures quite quickly.

[journeyman]

the 710's can afford to run less camber as they have rounded shoulders and an inflatable design with a stiff sidewall. BUT, camber angles are specific to what the car really wants not necessarily what they can afford to run. This tire was designed to keep the autoxer in mind that did not have adj camber. they do like to run the lower pressures as the inflatable design can "crown" with the higher pressures, giving you less contact patch with the road and increasing spring rate in the tire. the lower pressures with this particular tire give you more "bite"...which is nice for a tank slapper happy rear wheel drive.

in light of all this...it is a testing thing. i like to set the camber up keeping 2 important things in mind: optimum contact patch for cornering while not sacrificing too much braking ability and stability.

you can figure it out a couple of ways: use a pyrometer and measure the temp across the tire or keep adding or removing camber until you feel the car change for the better or worse.

[DECH_92]

There was a link on corner carvers to here!
http://66.59.135.81/forums/showthread.php?t=5996
http://66.59.135.81/forums/showthread.php?t=6238
I think one of the best references is here under our noses.
From the great new intimidator of Solosprint. :)

Your car being heavier only amplifies the problem. More speed, traction = heat buildup
Less air pressure seems to be the way to go.
Camber?
You’re going to have to be nicer to your competition. Russ has a tire temp prob. :D

[Dave Barker]

Well I can tell you, there is a lot of anecdotal advice out there. On one site from the US, I am hearing that V710s on vettes do very well with as little as - 1.6 camber and starting cold pressures of 25 lb heating up to 34 psi hot at the front for road race use.

OTOH on another site, a fellow with a 3 rd Gen Camaro is saying stay at - 2.5 and start at 38-40 PSi cold. Obviously wildly different settings.

Another fellow with a Camaro similar to mine has found that -1.8 camber and somewhat lower pressures work for him but I am not sure if he has compared lap times to V710s at different settings or if he is actually comparing just different tires in which case the V710 will be faster anyway. I'm sure a corvette doesn't need as much static camber as a Camaro but -1.8 seems pretty low to me.

So far Kumho has not answered their email.

[DECH_92]

I am no way near as serious as you guys have become, nor research as much.
Especially when the tracks you run need different camber and toe settings on different tracks.

Camber is set to maintain full tire patch on corners? Is it not?
When I started, DDT I had -1.5 camber with 255/40/17 on 8.5 rim, 30psi rear, 40psi front, V700 tires that left me with 3 inches of unused tire on the inside.
Then went up to –2.5 camber and still had 1 inch left untouched on the inside. My tires would last forever at these settings. The little tire temp reading I did do, they were all reasonably close in temps.
This year after lots of modification to the strut tower and struts I am going to run –3.0 camber and hoping that puts me at full contact patch.

With your better front suspension I assume you were getting full contact at your –2.5 camber so why would it change much switching to V710`s of the same size?
We all know that the only true way to find out proper Tire PSI is with a temp probe so I don’t see why it will be hard to figure out best tire pressure. Unless you run lots of toe in or out that will make reading the tire temps a little harder.
I was going to go toe out this year but I think I will go with zero and buy a tire probe and do lots of testing this year.

Those camber setting you listed sounded way to low.
I guess when you have sticky tires like the V710`s and you only use them for 3 to 4 events (16 heat cycles), you can run almost any settings. At least till you cord the outside.

[Dave Barker]

Greg, my car doesn't need as much static neg camber as yours. OTOH neg 1.8 does seem too little to me if the V710 has a very stiff sidewall (which I gather it does). The real eye opener is the wildly different suggestions I am getting re-pressures as these tires are a bit expensive to "experiment" with.