Tire pressures

[Jack Gifford]

I need a tire pressure recommendation for my F/BFL lakester. Four identical tires, Goodyear FrontRunners (not the LSR ones), 28" x 5", not shaved. Car weighs 2070 with fluids but no driver, about 60%/40% rear/front. Front suspension but rigid rear. I'd be lucky to see near 200 mph (Loring record is 206). Loring track is quite nice.
I've only run 35 psi for dragstrip testing (under 100 mph). Would something like 45 psi be appropriate?

[Dynoroom]

Tire info can be funny. Talk to people who run what you run. That being said, I have run those tires at 60 psi but with a heavier car (3500). If the pressure is too low the car can wander & it just gets worse as you try to catch up...

[Lemming Motors]

I was noodling this a while ago and came across a reference on tinternet that the Frontrunners have a max cold pressure inflation of 45psi iirc but that probably assumes drag racing, on the front, on pavement, so may be completely meaningless; at least for LSRs Goodyear include a pressure chart on the pdf brochure; 70psi for my fronts.

There is a thread on the Forum but I don't know how to provide the direct link so here is its title which might be searchable.
Landracing Forum ?Tech Information ?Steering - Suspension - Rear End ?Tire Pressure recommendations (Read 19913 times) started May 2015 which may be useful.

[Stan Back]

Yeah ? I know it's a Street Roadster.  But with 1400 pounds on the front we ran the 3.5x15 M&Hs at 45 to 55 pounds.

As an aside, earlier we set the record at 199 with 25-inch Goodyears.  Later that year we switched to the 21-inch M&Hs and got in the 2-Club at 201.  Later recorded at 206 and 210.  As I remember, we lost 82(?) sq. in. of frontal area.  Of course this is spinning area, so who knows?

On my car, the M&Hs always felt more comfortable steering.

[John Burk]

Aside from handling and casing strength I read that the limit on tire speed is that the flat side from ground contact needs time to recover before it reaches the ground again . Too many MPH for a given PSI = rapid heating . The greater the internal pressure the smaller the flat spot and less time to recover . Why LSR tires are light and stiff .

[ronnieroadster]

Jack the drive tires on my race car are 28 inch tall Moroso brand front runners  at Loring I run 45 pounds pressure. In the past I used Goodyear funny car front runners on the front of the car also at 45 pounds pressure. The car has run over 200MPH at Loring our car weight is a lot more than yours. When we run at Loring we have the exact same set up as we ran at Bonneville. Were heading up to Loring for the July event hopefully we will see you there.
 Ronnieroadster

[Jack Gifford]

Thanks for the help guys!

[tallguy]

Aside from handling and casing strength I read that the limit on tire speed is that the flat side from ground contact needs time to recover before it reaches the ground again . Too many MPH for a given PSI = rapid heating . The greater the internal pressure the smaller the flat spot and less time to recover . Why LSR tires are light and stiff .

John, it seems to me that a smaller flat spot should result in MORE time to recover.  Would you mind enlightening me about this
with an explanation?  Thanks in advance.

[racergeo]

   I've always run 80 lbs in my drive tires. At the end of a run on a 105 degree day, by the time I get stopped and out of the car the tires are about 110 degrees. About the same as the salt. Lee Kennedy used to check my narrow front runners and found the same thing. If you don't spin your tires they don't get hot on the cool salt with moisture coming up.