this was from the suspension thread on an rx7 forum..

"If you want the best handling possible, then choosing the largest wheel size/ lowest tire profile combination is what you do. If you don't change the outside diameter by doing this, then you don't have to change your springs. If you did (which means you have a larger contact patch for better grip), you would have to install springs which lowered your car back to its original ride height (or even lower for better handling.)

The only trade off in converting to a larger wheel, lower profile tire, is that the ride will be a little more firmer feeling, which means you feel the bumps a bit more.

Nonetheless, it's the only way to go if you want better handling."

then he followed it up with:

"If you are accostumed to older style "high" profile tires, then you will definitely feel quicker and more accute steering feed back when changing to low profile tires. THIS IS DESIRABLE FOR ANYONE TRYING TO DRIVE A CAR AT OR NEAR THE LIMITS OF ITS TRACTION.

As for a larger wheel increasing unsprung weight:
1) sport or racing springs counter the added weight of a larger wheel.
2) racing wheels are lighter than stock wheels, even if bigger in diameter.
3) A low profile tire is lighter than its high profile counter part.
4) Even a slight increase in unsprung weight is an acceptable compromise to increase your contact patch, and improve lateral stability.

The Bottom line: THERE IS A REASON WHY HIGH PERFORMANCE CARS USE LARGE WHEELS WITH LOW PROFILE TIRES."

I especially like point number 1..

 

it all makes sense now, im buying the 20s ive been looking at for so long

 

The ONLY reason for going to a "bigger" wheel is for bigger brakes/rotors. Ed

Which is one of my last problems. ...... . . . . . .......

 

Did you put him in his place rO@R?

 

I like how number 2 doesn't contradict number 1.

It is clear that this person as a grasp of mechanical concepts that are way behond the comprehension of commun mortal and I would appreciate you not laughing at his genious.

Now, this being said, I am out of here, I have to go buy 20" Fittipaldi wheels and bigger springs.


[Modified by JPP, 10:16 AM 10/18/2002]

 

my reply
edit: see I was trying to be nice, before I wrote "he knows absolutely nothing".


[Modified by Dave-ROR, 10:40 AM 10/18/2002]

 

Whats the site/thread? Lets all go lay the smack down

 

I left that out for a reason. I'm not a fan of starting fights between boards, too many trolls, etc will result.

 

Dave you are getting boring and not as much fun anymore

 

At least he still drinks beer, pansy

 

Larger wheel diameter with lower profile tire yields greater contact patch? hmm... very interesting indeed.

 

I have to concure.

 

Concur?

 

hah.. where ma "duece treys" at...

 

haha thread was locked after he replied to me.

his reply was:
"Dave,

If you read the thread carefully, you'll note I did mention that my first response was in reference to prototype cars (e.g. F1, CART etc), and not an RX7 street/track car. So, I appologize for suggesting the 18" wheels would be preferred to the 17" wheels.

Regarding your comment "DoubleDown doesn't know what he's talking about", my points made about lower profile tires giving better steering response, and larger diameter tires giving a larger contact patch, are CORRECT, proven by the trend in wheel size/tires over the last 20 years on sports cars has been to increase wheel size, and decrease tire sidewall height.

For drags, low profiles are not preferred, so if madrev uses 15"s over 17"s, understandable. But if you want to tell me that 15" are better than 17" wheels for track events, the only one sounding like he doesn't know his stuff is you."


mine through PM was:
"want a fun project, go find me a single SCCA road racing RX7 that runs 17s or more except to clear bigger brakes on things such as SPO cars. You wont find any, and there's a reason for that.

We run a road racing RX7, so I do know a little about setting them up, and bigger wheels are far from advantageous for anything but looks and big brakes. The only bad thing about 15" wheels is the lack of tire width available except for drag slicks.

F1 cars use 13" wheels btw, at least according to the formula1.com car specs.

Also, larger tire diameters do not provide more contact patch. A tire with a larger section width will.

Our road race car runs 13s, it will never run more than that. I run 15s on my personal car that sees track events and I'd never even consider putting 17s on it, especially for autox or track events.

I'm not trying to be an ******* but I have this thing against misinformation, sorry."

good stuff. hehe

 

"I'm not trying to be an ******* but I have this thing against misinformation, sorry."

haha, sig worth quote.