[Shotimes] my 89 SHO Sr 72 update

[Leigh Smith]

Ditto here;

Drag racers still prefer 15 in dia wheels for that reason, they 
accelerate faster than a 16 in dia wheel, all else equal.

Ultimate cornering power is just the opposite, the larger the diameter 
the wheel, and the wider it is, the more cornering power the car has. 
The wheel edge simply moves closer to the edge of the tire at the road 
surface. IFIRC I think diameter counts for almost as much of an 
advantage as width. All else being equal, ie: tire diameter. Shorter 
sidewalls resulting from a larger wheel are a tremendous advantage.

Ultimately the best road racing setup is a compromise between corner 
exit acceleration vs cornering power speed.  It wil vary from track to 
track, even with the same car. IFIRC  the Formula one cars change tire 
sizes from track to track.

Also there is a big catch:  wider wheels, lower profile tires, and race 
rubber (vs street), are all progressively more sensitive / demanding of 
correct suspension geometry and alignment.

I remember an article where the exact same mid 80s Corvette actually 
 went slower on pure race rubber, vs street tires, at Laguna Seca, 
because it wasn't tuned for them.

I have seen 12 in wide race slicks on an autocross car with 10 inches of 
it in the air due to lousy geometry! duh! And he could not understand 
why it was so slow and hard / demanding to drive.

So how fast do you want to go??? (Speed costs money!!!)

Lee


Ron Porter wrote:

>Somewhere back in my "archives" I have the article that Sport Compact Car
>did with various tire/wheel combos on a car wrt weight versus performance.
>
>What was also interesting that one 17" combo weighed the same as a 16" combo
>in static weight, both were the same overall height, but still performed
>more poorly. The reason is that a lot of the weight of the combo is in the
>rim, and the 17" combo has the rim farther from the hub, so the dynamic
>rotating weight is actually higher than the 16" combo.
>
>Ron Porter
>
>-----Original Message-----
>From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
>On Behalf Of Mark Nunnally
>Sent: Friday, September 12, 2003 11:24 AM
>To: shotimes@autox.team.net
>Subject: Re: [Shotimes] my 89 SHO Sr 72 update
>
>
>  
>
>>One restriction I have is my rims and tires. 16 inch.
>>    
>>
>
>nothing wrong with 16" as long as they are wide!
>
>I run (and will always run) 16's on my 89 for the track.  cheaper track
>rubber, and I like the better "gearing" of the shorter 16" sizes (225/50 or
>245/45) compared to the stock height taller sizes with 17" wheels (and most
>likely heavier)
>
>mark
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