Re: over/under - steer and tyres

[QSHIPQ@aol.com]

In a message dated 5/22/99 8:45:43 AM Central Daylight Time, JustaxPHX writes:

> One other point:
>  
>  > The problem is, this affects the operation of the awd system itself.  
> Different size tyres on a locked front to rear, you > goes noplace.
>  
>  This isn't necessarily true; it's the *diameter* of the tires that matters 
> with a locked center diff, not their width or profile.  I successfully 
drove 
> my Ur-Q with a locked center diff and 235/40s up front and 215/45s on the 
> rear but that's because the measured difference in diamater between them 
was 
> only 3mm or slightly less than .5 percent.  If there was such a tire, I 
could 
> run a 375/25 in place of either the 235/40s or the 215/45s, and it wouldn't 
> make any difference to a locked center diff since the overall diameter is 
> essentially the same... 
>  
>  JG 

Interesting point.  I wonder what the max allowable difference would be.  
Since a 3.89 front hooked to a 4.11 rear will lock (btdt), that seems to 
indicate 5% is a no.  I'm also suspicious that excessive drivetrain/tire wear 
occurs even in the small differences.

I'm not game for the experimenting, but those really interested....

Scott