Best tire size for road course with 16" rims
 

I have 205/40R16 tires on my 16" rotas. now those tires are way to small. I bought the rims used and they came iwth the tires. i have no drop. I want to get a bigger tire. One that will help fill the wheel well gap and look good. i'm really getting sick of the small tire and the horrible ride. Thanks.

look good or go fast? the 2 are contradictory.
Bigger problem is the lack of good tires in 16" sizes. You're gonna have to choose the size based on whats available, I doubt many of them are going to look good, just pick one that fits.
I ran 225/45/16 hankooks last year, which fit well on 8" rims, but I can see them being awfully flubby and squishy on a 7" rim. Try 205/50/16 or 215/45/16

whats the difference between those two tires? what would you do in my situation?

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Width/Sidewall/Diameter of Rim

205/50/16 has a smaller width, larger sidewall and same rim sized compared to 215/45/16

Btw I would always try to go wider, as for side wall...I generally go smaller because you tend to have stiffer sidewalls.

with a stock motor, I'd go for the gearing advantage. With lots more power, I'd take a taller tire, power won't be an issue,but traction will. Taller gears will help quell some of the issue.

The sidewall # isnt a fixed number... its a ratio.

Example;
A 205/50-16 has a side wall height of 4 inches.
A 215/45/16 has a side wall height of 3.8 inches
and for compairson,
a 225/45-16 has a side wall height of 4 inches.

I knew it was a ratio, but Im not sure of what the ratio is between. I always thought it was just rim diameter, but clearly not from the example you give above.

THe ratio is based on the section width.

Meaning, on a 215/45 tire, the side wall height will be equal to 45% of the section width. 215mm = 8.4646 inches 45% of 8.4646 = 3.8 inches.

Can you explain what rob is talking about with gearing and size wall size?

Thats actually quite a bit easier....

Your tires overall diamiter influence the final drive ratio of your cars transmision. "Shorter" tires will shorten the gear ratio, and taller tires will Lengthin the gear ratio. Shorter gearing will typically improve acceleration, at the cost of top speed, where Taller gears will hamper acceleration but increase your potential top speed. (Great article on it, thought it deals primialry with drag racing, but it still applies to circuit racing)

Very cool...now how do I calculate the differences and how it will effect my 0-60 times?

Ummm 0-60 times? What kinda racing are you trying to do? The only time you're doing 0 is in the pit lane. I don't think any of us have actually timed out the difference, since all any of us are concerned about is how fast you can get the car revved up to the point where it actually wants to pull its own weight, which is what shorter tires do. Since you're limited to the tire sizes you can buy, the only thing you actually have to realize is what spencer told you... shorter than stock = acceleration, taller than stock = top speed. Take the acceleration. The shorter the tire, the bigger the gear advantage. Honestly, if you want the acceleration to be its maximum, keep the tires you have. Thats the shortest 16" tire you can buy. So theoretically, you have the "best" tire you can get from a tracking stand point, provided that it can handle the load rating of the car (which it probably cant). So step up one size taller from there... which is either 205/45 or 215/40, then 215/45 where you should be able to find something... one of those is a stock Lotus size.