Re: [DML] Tires

[Mark Noeltner <mark@xxxx>]

At 10:07 AM 11/8/00 -0500, you wrote:
>Understeer in a rear-engine car? Under what circumstances did you experience
>this?

I've experienced understeer in this car also. That's the whole reason Lotus
and DMC specified the much larger tires on the rear. To get rid of the
oversteer inherent in a rear-engine car and instead have a slight
understeer condition like most other cars on the road. Much safer for the
average driver. You're only going to notice it if you push the car out to
it's limits. I doubt that many DeLorean drivers do this. I autocross ours
about twice a year just so I know how it will react when driving at the limit.

>> Has anyone considered/tried putting softer tires
>> in the front than in the back - ie
>> Yoko A520 in front/Yoko AVS intermediate in the rear?
>
>As we have heard frequently in the news lately, if you run your tires at any
>pressure other than that specified by the automobile's manufacturer you might
>create a safety hazard. Perhaps it is possible to run a "softer" tire at a
>pressure that will give adequate safety, but I have no idea how to determine
>this, and I do not even know who to ask. I would be afraid to trust the
advice
>of an anonymous person on the internet.

Mike, Jim didn't mention anything about tire pressures in his post. I think
you're reading something that isn't there. He's just asking about running a
softer rubber compound which doesn't imply anything about tire pressures.
You CAN adjust handling with tire pressures, but he didn't ask or mention
that.

Jim, the only way to determine if this will work is to test it. Personally,
I would recommend taking it to an autocross, or to a track if they have any
open track days. This way you could test the tire combination in a
relatively safe environment rather than out on the road. With the stickier
tire on the front (the A520) it should theoretically even it out a bit. But
without testing, who knows?? Be sure to test it in the rain so you know how
it feels. In bad weather I'd much rather have understeer than oversteer.

You can also get rid of some of the understeer by raising the rear tire
pressures slightly. It isn't helping your ultimate grip any, but it will
let you adjust the feel. The DeLorean has fairly wide tolerances on tire
pressures. For road driving, as long as you keep the front and rear within
the limits in the owner's manual you'll be pretty safe, even in bad
weather. For performance driving on dry pavement you want to stay near the
upper numbers they have in the book. That way tire rollover in cornering
will be minimized. The Yokos probably need a slight adjustment to the
pressures to get the handling closer to neutral anyway, compared with the
original NCTs. Different rubber compounds will react differently.

>
>Who should answer Jim's question? If a person claimed to me that they could
>improve handling by changing my tire parameters, what sort of credentials
>should he/she present before I listen to him/her?

You have to make that judgement.
>
>- Mike Substelny
>VIN 01280, 7 years

Mark Noeltner
VIN 6820 - only 2 years
SCCA member and autocrosser - many more years