Here are some additional things to think about.
I used to use the 18x7.5 fronts and 19.5x7.5 rears before changing to
18x7.5's all around. The car was almost the same to drive either way, but
the acceleration was slightly less with the tall rears. The car also felt
slightly more "squishy" with more overshoot in a slalom with tall rears due
the larger slip angle in the rear.
With a lighter car than F500, or a F500 with the motor centered better
(motor up against firewall), this effect might not be noticeable.
Chuck
From: "Sheldon Lemoine" <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: [F500] Re:Tire Question
Date: Sun, 29 Apr 2007 11:19:06 -0700
We Canadians are part of vast international conspiracy, orchastrated by the
SCCA, to kill off F500 by moving all cars north of the boarder...or perhaps
the Rotax engines feel more at home in the great white north...
I don't have a definitive answer to the tire size question since I've
always
run 19.5's on the Mk V, but your description matches my understanding.
With
our very limited suspension, the spring rate and deflection of the tires is
important. Hoosier provides some data on 10" tires for FSAE cars (same
tires we use) and it shows that the spring rate of the 18 is slighly higher
than the 19.5, especially at lighter loads, and that the 19.5 also deflects
a bit more. See https://www.hoosiertire.com/spring.htm for data.
I suspect that the 18 may offer the potential for faster runs in autox due
to crisper transitional response, but the 19.5 is likely easier to drive
closer to the (slightly lower) limit consistantly.
All that said, many of the fastest drivers in autox use the 18 and Hoosier
Tom suggested that it is probably the better tire for solo...someday I hope
have some spare tire budget to test the theories.
Sheldon
On 4/29/07, John Vriesinga <[EMAIL PROTECTED]> wrote:
>
> What's this? Yet another Canuck?
>
> That would make 3 or 4!
>
> Anyways, with regard to the tire question what I overheard yesterday,
from
> someone who should know (I sure don't) is that they are more squirrelly
> than
> the bigger tire. The taller sidewall makes the bigger tire more
forgiving
> than the shorter one, is what he said, complaining bitterly about
getting
> beaten round the track by his daughter.
>
> YMMV
>
> JV
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