In looking at various tires to replace my runflats, I have noticed that the specs indicate a wheel width range for the various tire sizes. Usually the spec'd tire is based on the middle of the wheel width range.

So what is the effect on performance if one uses the same tire on a wheel width in the upper end of the range?

Specifically, I am looking at a 205/50-16 which is spec'd at 6.5" wheel width. The range spans 5.5" to 7.5". What will be the performance difference (positive and/or negative) of going from a 6.5" wheel to a 7.5" wheel?

TIA,

Theo

 

Anyone?

Theo

 

the wider the wheel will allow the sidewall to stand straighter, giving you better turn in.

 

Koopah,
Generally we look for a "perfect fit" for rim and tire. So in your case a 205/50-16 tire has a range of widths it can be mounted on with the perfect size to be for a 16x6.5" rim.

You can use rims that are 16x5.5" but the tire once mounted will be about 0.4" less wide than when you mount it on the 16x6.5" rim. If you use 16x7.5" rims then the tire will be about 0.4" wider than on the 16x6.5" rim. So if you want the widest possible tire to increase cornering traction then a very wide tire and a very wide rim would be best.

However this adds more weight (wider rim and tire), cost and rolling resistance so lower mpg and it affects acceleration. The narrow rim and more narrow higher side wall tire will be more comfortable, lighter, cheaper but not perform as well.

So for commuting and general use rims that are about 5.5 to 6" wide are usually OK.
For autocross and track 7 or 7.5" is common, easy to find and not too heavy. Custom rims start from 8" wide. 6.5" rims are inbetween and common in 15 and 16" wheels.

 

unless you're racing, the answer is minimal. very minimal. You'll be hard pressed to notice the difference on the street.

 

Thanks Philpug, ripley and (as always) minihune!

I'm trying to find a lightweight (<= 15 lbs) white wheel in a 16" size. I like the look of the Koseis, but they are a 7.5" width. The NZO Monzas are roughly the same price but are about 4 lbs lighter and come in a 6.5" width. Problem is, I think I like the look of the Koseis better. There may be others out there...

I will be autoxing a few times this year but will mainly be street driving. One other consideration is the tire I am considering: the Goodyear F1 GS-D3. I have heard that the sidewall is a little soft so perhaps the 7.5" wheel would be of benefit to that tire.

Thanks again, guys!

Theo

 

What class of autocross are you participating in? If stock class then you'd need a stock sized rim 15x5.5, 16x6.5 or 17x7 with wheel offset close to stock.

If you are in a different class then there are other sizes that are legal.

Try shopping online at tirerack and see what comes up for white wheels in 16".
Or you can call Alex@tirerack for more info.

 

I'll be competing in ASP since I have the JCW 210 kit. I think the door is pretty wide open.

Theo

 

In ASP you are free to pick any wheel diameter, width and offset.
For white and lightweight you might check out Rota wheels (available through Rspeed)
An example is the slipstream in white 16x7" +40 or +45mm offsets, replica of Spoon wheels, 13.5 lbs each about $500 a set of four
http://www.jaydm.com/assets/img_thumbs2/whtslipside.jpg
Grid and Circuit 8 are also in white and 16" weighing about 16 pounds.

If using the wheels for mostly street and some autocross the Eagle F1 GS-D3 is fine in 205/50-16 and so are 215/45-16 Falken Azenis Sport tires. The Falken RT-615 doesn't come in a good size for 16" wheels (205/40-16).

Other legal upgrades in ASP are:
Quaife differential
Front camber plates

 

I have a set of the White Kosei's in 16x7.5 with the Goodyear F1 GS-D3 205/50/16's. They are my everyday street set. They weigh ~34lbs.
They are a great combination. I can go out and push the car in the twisties with confidence. I have never autocrossed on them.

For performance/racing you want to get more tire patch on the ground so wider is better.

 

sorry for the hijack - dpayne1 - email me, Your phone # I have is disconnected.

Alex