Most tire manufacturer's websites say that for their 205/50 tires the optimal rim width is 6.5". Why then does it seem like everybody is putting 205/50 on 7-7.5" rims? Wouldn't the tire perform best on a 6.5" rim? What are the advantages and disadvantages of putting tires on wider or narrower rims than is optimal? In other words in addition to my question above I'm also curious what kind of effects putting a 215 on a 6.5" when a 7" is optimal would have?

 

w/a slight stretch cornering is optimal, but u dont want to go to aggressive

a half inch is kool, no big deal there (215 50 on a 6 1/2-7.0" w/enough side wall should be fine. its when u go w/less side wall that u might run into a prob.

 

6.5" is NOT the optimal rim width for a 205/50 tire, it is just an industry standard for that size tire and is designated as the "measuring rim width". Very few tire makers will tell you the optimal rim width for a tire. If you go to TR's web site and look up Hoosier A3S04's or A3S05's you will see that the optimal rim width is often wider and sometimes much wider than the "measuring rim width". Optimal width will vary from one tire model to another even in the same size though. Generally you should be not more than 1" below the max rim width for best tire performance. Autocrossers will almost always go for the widest rim width that will fit the tire because it will handle better. On a very stiff tire like Falfen Aazenis 215's you give up very little by being 1/2" under max width but the difference will be more noticable with softer tires.

 

^^^ wat he said. :smile:

 

Also, installing too wide a tire on too narrow a rim decreases that tire's optimal contact patch width; because more of the tire is required to reach the rim. This invariably causes the outside edges of the tire to lift. This also weakens the sidewall.

IMO 205s belong on no less than 7" and 215 on no less than 7.5". Increasing rim width by a half for each of the above examples may (because it depends upon the tire) actually aid sidewall stability, and, increas the width of the contact patch.

Wider is only better in some circles...

 

so then i should be safe running a 205 40 on a 7.5 wheel (toyo tyres of course which are built for stretching ) i know its a bit off but i've looked up their measurements & it seems to me like it should be kool....i run 215's now & their great but need it to look a little more aggressive...plus i run a wheel w/a NiCE size lip so w/an aggressive stretch this combo looks killer!!!

 

I was incomplete - 205/45/17 on a 7" and a 215/40/17 on a 7.5"

 

hmmm...not what i wanted to see but ok! thx for advice i will be goin' to a 45 for the 205 stretch on a 7.5" wheel i will post if i run into any problems

 

205/40-17 will fit rims 7 to 8" wide so 7.5" rim is fine.
Load rating is really low for a MINI compared to stock(80W or 992 pounds).
Good for "one person" in the car and for track or autocross use only.
Talk to Alex@tirerack.com before you decide to do this.

For 205/50-15 or 205/50-16 tires, rim width can be 5.5" to 7.5". 6.5" is a "good" fit but optimal is a relative term depending on what you intend to use the tires for. If for street driving then 6.5" rims are fine. If you have only the stock 15x5.5" you can still mount this "wider" tire on the narrow rim but it would be tougher for your installer and the tire would run a bit more narrow than if you used a wider rim. If you use a wider rim say 7.5" you can still use this tire but the tire section width will be changed wider.

See
http://www.tirerack.com/tires/tirete...skey.jsp#depth
For every 1/2 inch wider or more narrow your rim(than the "measured rim width"), your section width can be affected by 0.2 inch wider or more narrow. Sometimes the change varies with the stiffness of the tire sidewalls.

 

Absolutely! The best track combination I have had to date I feel was my 205-40-17 on a 7.5" rim. This is within the Toyo recommendations for their RA1s.

 

yea that's on their RA1's i did see that, but for their gen4 proxx tyre they dont list it as being favorable dont know why its the tyre right under their rA1's....

 

thx d0oD!!!

 

One thing to remember for street use is rim protection. An 8" rim is measured across the inner lips, with most ~ 1/2" thick. So an 8" wheel measures ~9" across edge to edge. A 205 section tire is 205/25.4 = ~8.1" wide depending on brand. Even adding the +0.6" fudge factor from being on 1.5" wider wheels brings us inevitably to the conclusion that 8" wheels are actually wider than 205 tires. I thought Mini was pushing it by putting the oem 205s on 7.5" S-Lites, and there are a lot of people in Mini Talk sad about 'kerbing' their wheels. Such is the price of performance, but you'd have to be pretty good to notice a performance difference. For me, 205 is just fine on 7" and 215 on 7.5".

 

know what ur saying on rim protection toyo tyres have a good rim guard on them believe u me i know! im real carefull w/my wheels but its not easy.....