explanation on wheel and tire sizes

[ishido]

I have a bunch of questions.

I'm looking into gettin a new set of wheels. Chances are they will be very light compared to stock. What I'm debating on is size. Stock is 16x7 I believe and I was planning on going w/ that size or slightly wider 7.5 maybe 8.

1) By going wider, is this going to give me any advantages? Will I be able to go to a wider tire size? If I stay in the same tire, but wider wheel, what are the effects?

2) What are the advantages/disadvantages of going w/ bigger wheel diameter wise (17 or 18)? Is having a large diameter, with small aspect going to produce some side effects (wheel hop, slipping, worse handling)?

3) I've noticed that a lot of Type Rs in magazines actually go w/ the 15" diameter wheel. So this is the opposite of #2... why go w/ a smaller wheel?

4) What wheel size and tire size do you use? why? and what do u use it for?

Thanks in advance

[nxracer]

A lot depends on your use of these new wheels

With the intake your car is already out of SCCA stock class so I'll assume STS

STS is limited to a 7.5" wide rim of any diameter that fits.

1) if your going for a 225 tire (max allowed in STS) you would be best served by a 7.0" or 7.5" wide rim.

2) bigger wheels almost always weigh more plus you'd need rubber bands for tires to keep the actual "rolling diameter" close to stock. THe other drawback to "big" wheels is P O T hole damage, if your roads are full of pot holes expect to buy lots of rims.

3) they use the smaller wheel (actually the stock size) to keep the rolling diameter small. A smaller rolling diameter will get you on the seconds cam quicker and in a GTS that is where you want to be.

4) I drive a GT but most GTS drivers run about the same setup. 15x6.5" wheel with 225/45 tires, others run a 225/50 or 205/50. The 225/45 is the smallest tire/wheel combo you can build. With my stock (came on the car) tires I hit the rev limiter in second gear at about 62 miles per hour, with the 225/45's the limiter hits at 55.

BTW the stock wheels are 6.5" wide

[ishido]

I'm looking at STS class, but really just wanting the best combination for all around, not just SCCA.

I'm def. going to stick to 16s, prolly 16x7. Was looking at some Kumho ECSTA Supra 712 to go with. They have several different sizes, so I'm debating between them.

205/40, 205/50, 215/40, 225/45

A) Any problems with just going w/ a smaller aspect ratio?

B) Or should I try to get the widest rubber I can put on (225/45 or 215/40)?

C) 205/50 has a listed diameter of 24.1" (on Kuhmo Spec Chart)
225/45 has 23.9"
215/40 22.7"
205/40 22.4"
While the last one has the smallest rolling radius, am I going to experience any major side effects? Speedometer inaccurate, harsh ride, or too small of a radius?

D)will also being going to Drag Strip-any major changes w/ a new tire ratio?

[nxracer]

A) Other than the Pot holes and giving your tire mounter fits. No!

B) I currently like the 225 others like a thiner tire

C) With the 225/45 or 215/40 the speedo will read a couple miles per hour faster than your really going

D) Don't know I don't drag race (don't look good in the dress)

[erok]

There are a lot of conflicting opinions on this subject. The speedvision type Rs used to run 15's but now I think everyone there uses 17's. I read in SCC that this years Speedvision Series winner won with 15's and 225/50 series tires because they couldn't get the 17's to fit their car right. Grassroots Motorsports mag did a comparison with "plus sizing" wheels while using lower profile tires and the fastest lap times were gotten with a +2 set up; I think 17's with 215/40 series on a Civic.

If you take all the factors into consideration, including climate, cost, performance and longevity, probably the stock wheel and tire sizes are perfect. One thing I'm sure we can count on is that the Toyota engineers considered all the possibilities.

My guess is that the best performance combination would be to stay close to stock and adjust depending on the road and wether conditions you're likely to drive in. 15-17" wheels with between 6.5-7.5" widths and not less than 40 series tires. Any combination heavier than stock (about 39lbs for wheels and tires) will definitely not improve performance.

I'd love to try some lightweight 17x7.5 wheels with 215 or 225/40 series tires. I think that would be a fast combination for autox and road courses.

BTW: The Kuhmos may last longer than the stock tires but IMO they don't perform as well.