Tire pressure

[tmoretta]

I am looking for suggestions for tire pressure from builders with completed cars. My 818S is showing some handling problems. Specifically tramlining or wandering which is a little scary to drive on other than completely flat roads. I am currently running 20 psi front, 24 rear tires (215 40/17, 245 40/17 on 8 and 9 inch wheels). Are my tire pressures too low?

[billjr212]

there is another thread on this topic. check it out here: http://thefactoryfiveforum.com/showthread.php?11323-Tire-Pressure-Discussion

and another shorter one here: http://thefactoryfiveforum.com/showthread.php?18627-Tire-Pressure-and-Brake-Bias-Initial-Settings

Bottom line thinking is to start around 20 psi all around and adjust from there based on scrub/grip/handling/etc.

[Rasmus]

Some tramlining or wandering is to be expected with such a light car....

However. Anything above a "modest" level of either the first thing I'd start to look at would be the toe settings. Running toe out in the front can make the car want to follow the tramlines and drive down the crown. Rear toe out can make the car want to follow the tramlines even more plus it'll be twitchy, where the driver has to constantly be on top of keeping the car going in the desired direction. Rear toe out would make an 818 (mid engine/rear weight bias) prone to snap oversteer and lift-off oversteer. It'd be a handful at anything over 45 mph.

[philly15]

as stated what's your alignment look like, and what do you have for tires? either way unless you're on full slicks, that pressure seems pretty low to me.

[Wayne Presley]

On the Lotus Elises I ran 19-20 front and 20-21 rear with DOT R tires. I ran the same on the prototype 818s during testing with good temp gradients across the tread.

[Bob_n_Cincy]

On the Lotus Elises I ran 19-20 front and 20-21 rear with DOT R tires. I ran the same on the prototype 818s during testing with good temp gradients across the tread.
Wayne
Was that cold or hot temps.
Thanks
Bob

[Wayne Presley]

Cold, the offsets depended on whether the track was clockwise or counter clockwise.

[Bob_n_Cincy]

Cold, the offsets depended on whether the track was clockwise or counter clockwise.
Thanks Wayne
Any memory of track temp and hot tire temps.
Bob

[Wayne Presley]

I'm in the south so ambient temps were usually in the 90's and tire temps were in the 150-170° F. Hot pressure ended up being 27 psi.