Hoossier Tire Pressures

[Deon]

Is there a recommended tire pressure for the Hoosier Slicks?

Thank you,

Deon

[Steve Davis]

Deon,
Not sure, but suggest you start off with 18 front, and 20 rear. Check your wear patterns after that and adjust pressures accordingly for your specific car and driving style.

Steve, FV80

[FVRacer21]

Deon,
Not sure, but suggest you start off with 18 front, and 20 rear. Check your wear patterns after that and adjust pressures accordingly for your specific car and driving style.

Steve, FV80

Steve,

When I asked Hoosier their comment was "Hot pressures of 22 front, 23 rear" for max and adjust from there.

How does that match your findings?

ChrisZ

[10rmotor]

We use a completely different tire than you (DSR/P2) but we have found that the pressures come up about 4-5 PSI when hot, and so we start out at 14F/16R to get to our optimum of about 18/20.

[azjc]

I've been starting out with my Reynard FC at 14F / 16R cold & finding 16.5F / 18R hot off the track works well - anything higher and the tires seem to go off towards the end of a 30 min race. If only a 15 min session I add 1 psi.

[Steve Davis]

Steve,

When I asked Hoosier their comment was "Hot pressures of 22 front, 23 rear" for max and adjust from there.

How does that match your findings?

ChrisZ

I was quoting COLD pressures. I have NEVER checked HOT pressures since I have no one in the pits to perform that function. I just look at the tire wear indicators (depth dots and 'sliding rubber' indicators) and adjust slightly from there. The Hoosier HOT numbers are probably pretty close to what my COLD numbers are.. but you cannot 'set' HOT pressures.. you can only SET cold ones :-).
The pressures from the WIDE tires guys aren't really relevant due to the extra WIDTH of their tires. The run several PSI LOWER than vee tires.
Steve

[Hardingfv32]

[QUOTE=FVRacer21;664722]Steve,

When I asked Hoosier their comment was "Hot pressures of 22 front, 23 rear" for max and adjust from there.[QUOTE]

A 3 lb gain cold to hot sounds right for a average temp condition day... say 70-80 deg ambient day.


Assuming a start differential of 2 psi frt vs rear, I would expect the amount gain to be equal frt and rear. An unequal gain possibly indicating one end is working differently than the other.... handling imbalance?

Has anyone done any testing with much lower cold pressures, say 13 frt/15 rear? We did and found that it did not effect the lap time. I was looking for a temp gain.

The FVS compound as used on SM run at 200-220, while I measure 160-180 on a FV. A front line driver of both SM and FV says the SM tire has wonderful grip and the FV tire is terrible.

Brian

[Steve Davis]

...
The FVS compound as used on SM run at 200-220, while I measure 160-180 on a FV. A front line driver of both SM and FV says the SM tire has wonderful grip and the FV tire is terrible.

Brian

I think it's only fair to NOTE that the SM tires are more than TWICE as wide as the FVS. Regardless of compound (the same) the tire width plays quite a large part in the GRIP it provides.
I might also add that FVS is not 'TERRIBLE' IMHO.. but it's certainly NOT as 'grippy' as the previous (NON-SPEC) version as evidenced by extremely few FVS records (only TWO that I'm aware of in USA) being set that are faster than the prior (almost spec) tire.
Steve

[Agitator]

To back up Steve, I ran the same cold pressures at most tracks as he's running on the current spec Vee tire. On a track like Roebling Road, where you have several high speed left turns, I would run a pound lower on my left front.

The hot pressures were nothing I registered when running vees...but maybe I should have. In FE2, hot pressures give me a ton of feedback on my setup. At the Super Tour events, Hoosier has several guys in pit lane that will take your hot pressures (and temps across the tire) and write them on a slip for you. My cool down laps at Super Tour events last year weren't exactly "cool", so that I could get fairly accurate temps/presssures right off the track.

With FV suspensions being rather crude, I'd be curious to see if folks see an appreciable pressure differentiation across the four tires - hot vs cold.

[Hardingfv32]

I SM tires are more than TWICE as wide as the FVS.

But, the SM weighs twice are much and probably has a CG twice the height.

Obviously the compound is working harder on the SM for it to achieve 200-220 temps vs 160-180 for the FV.
We have tried a whole range of adjustments and have seldom seen more than a 10 deg increase in temps.

This is using IR sensors to measure surface temps while on the track.

Brian

[Hardingfv32]

I'd be curious to see if folks see an appreciable pressure differentiation across the four tires - hot vs cold

If you are talking side to side, then yes it is not uncommon to see a 1 lb difference. I would question the benefit of correcting for that. While the pressure difference might effect the tire shape and spring rate a small amount, it does not effect the surface temps in the turns as measured by the IR sensors. If you are not in a turn, the tire surface temp goes back to almost track surface temp within a few seconds, Yes, the tire surface temps are greater for the outside tires, but the temp differential side to side looks the same for left or right turns. This assumes the turns are similar.

Brian