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Reply to "Tire Pressure again"

18 is TOO LOW for Danny!

Most of us don't have a VS Spyder. Most of us don't drive like Danny. Hell, most of us probably can't drive like Danny.

I think I set my Spyder's fronts to like 22. That seems pretty good. I'm running Vred Sprint Classics with tall sidewalls on that car. I plan to drive that car in a Danny-like way some before settling on final tire pressure recommendations. It might well go up a pound or two.

My TDR has Hanhooks or something, also 165/80s, and that car likes 16 lbs on the front.

That is because it is significantly lighter up front than a Speedster, much more so than a Spyder. With 22 lbs of front it's OK. A little stiff. 22 is about what that car wants for auto-x duty.

When I got it it had 30 up front and it was not only harsh riding, there was no front traction. I can report that 16-18 does not roll the tires off the rim, and does not squeal around corners.

Why would this be, you ask?

Because tires are made to be inflated against the forces (i.e. weight) opposing them.

This was true with bias tires also. Whatever sidewall you have—thick or thin, bias or radial, white or black—you want just a little more air on the inside of it than necessary to handle the psi forces it will be subjected to.

This is why the sidewall says "MAX LOAD" and a number. Look at that number on your tires. With a Speedster, it's going to be a number that's more than half the weight of your whole car (it's 1169 lbs on my Vreds; the whole car weighs 350 lbs more than that). And that's weird, huh.

On your daily driver or monster truck, the MAX number on your tire will be well less than half the weight of the vehicle.

But with our light clown cars, we're never going to get anywhere near the max load of any tire we run. Typically on street car tires, that max load is calculated at 35 psi.

So to make the tire work "right" on a clown car that weighs half or less than the types of cars it was designed to fit, we have to reduce pressure inside the tire. Yeah, sometimes to half that 35 lb "MAX LOAD" pressure rating.

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