[desousa: Re: S4 ]

[desousa@cisco.com]

From: desousa
Subject: Re: S4 
In-reply-to: Your message of Mon, 07 Dec 92 12:37:47 -0500.
             <9212071737.AA24463@ctt.ctt.bellcore.com> 
- --------
See comments below:

> From: Ramiro Reinoso <ramiro@ctt.bellcore.com>
> 
> I have 215/60HR15 Invicta GAs on the original BBS of my '91 200TQ.
> The handling is a little soft especially when cornering.  I'd like to
> get some new rubber and I saw Steve's posting that the BFGoodrich Comp
> T/A VR4 all-season tires are excellent.  I live in New Jersey so we
> don't see much snow.  Steve also changed the wheels to 16 inches.  Was
> this necessary ?  I read in a magazine (I think it was European Car)
> that the benefits of upgrading from 15 to 16 inches are debatable
> (they ran some tests and the difference was not there).  Steve, what
> was your criteria to get 16" wheels ?  What do you think it would
> happen if I get 225/50VR15 or 225/55VR15 tires ?  I want to see
> significant improvement, do I need the 16" wheels ?
> 
> Ramiro

Ramiro,
	Back in the early 80's, I worked for a suspension/tire/wheel company
that specialized in the +1 and +2 concept(upping the wheel size).   
In fact we did several 82 coupes and 4000 5+5's back then.  Stripped them
of the factory sway bars and springs.  Swapped the 13" wheel/tire setup 
for 15" and did a "real alignment" and wow, these cars handled superbly.
A decade later, and now its standard practice on most all performance
oriented vehicles. (bigger wheels that is)

By going to larger diameter wheels you could reduce the sidewall height but 
still retain the overall tire diameter.  Ie.. if you had a VW golf with 
175/70-13 you could move to 195/50-15 increasing your wheel size +2 from 13"
to 15".  Speedometer and gear ratios are unaffected but the sidewall of the 
tire was drastically reduced.  You've probably heard the story before.

	I didn't read the article but I imagine that the differences
between the 15's and 16's were not significant. Given that todays high speed
rated tires have stiff sidewalls, and the difference in sidewall height
is probably not significant, I could see that conclusion being reached.
Especially if you factor in the cost of new wheels and tires.
	If however you're in a position to change change or specify them, 
here are some of the reasons I would go for the largest diameter wheels 
and tires possible.  

a) Minimum sidewall means maximum response. (on the negative side stiffer
ride)

b) Bigger wheels mean more aluminum, less tire, therefore more heat 
dissipation.  (Which is your tire and brakes #1 enemy)

c) Bigger wheels mean more space between calipers and rotors, again
offering more heat dissipation.

d) My favorite reason, aesthetics. :)  The bigger diameter wheels have the 
illusion of making the car look lower cause the wheel is closer to the fender.
Also exposing those shiny rotors and hard working calipers.

Notice Corvette and Porsche going to 17" wheels.  And the 93 Porsche 
911s turbo has gone to an 18"diameter wheel!  (not sold in the USA)

happy motoring,
Carl DeSousa




------- End of Forwarded Message