i was talking this over with another S2K owner on ICQ. he mentioned the possibility of a smaller tire/wheel combo would greatly give us better acceleration (it's like a final gear ratio change without the hassles of tearing the tranny apart), and i thought so too. but after talking it over with an engineer who races on side, i don't know if the trade-offs are worth it. here's what he said in an email reply:

************

Richard,
Be carful. There are many factors that come to play when changing tire size.

To answer your basic question, centrifugal force related to a 15" tire
versus a 16" tire. The flywheel effect you refer to does exist but is very
small. The greater effect would come from what change was made in the
overall height or outside diameter of your new tire. If your newly selected
tire is smaller in height than the original then you are effective changing
your final gear ratio. Say your original tire is 25" tall. Your new tire
is 23" tall. You car will accelerate faster than before no question. 98%
of the reason being because your have added more "gear ratio", and 2%
because the tire is now a smaller flywheel and easier for your engine to
spin. The direct trade off for selecting this smaller tire is that your
cars final top end speed is now slower than it was with the taller tire.

Most people/racers select tire size according to their handling/riding
requirements. Depending on which way you go you are always going to
sacrifice something. So the trick is to find a happy medium.
********************

and i talked with him briefly this morning, he said that smaller diameter wheel/tire combo could also add much more stress to the tires. on top of losing top end speed (who going to drive 153MPH?), he also stated that handling might be affected, not to mention the stress/heat on the tires.

so, yeah, if you want faster 0-60 acceleration, the consensus is that you can do it with say 15" wheel and low profile tire combo, but is the trade-off worth it? don't know.

hope that was as educational to you as it was to me.

 

What if I put minispares on both drive wheels? Think I could run a 10 sec quarter mile? Maybe Rick will let me have his spare since he's not using it. Then I could go out and spank some Vipers!!

 

From what my understanding is: Yes you will accellrate faster, but you will also have to shift up sooner. So it will not benefit you as much.

The car will be more responsive though and feel lighter although i doubt 2% will be that noticable.

 

you could actually go a step lower with the 16's = 205/40 instead of 50, yeah you would also get a shorter contact patch. I think it would look funny with the large wheel wells.

 

Yeah, but you get to VTEC ealier . . . so it would be that much better. . . VTEC around 25 mph instead of 28mph . . .then stay in the powerband, if your trying to get to 65mph then it would screw you with another shift to get there, BUT if you were going to 80mph you would be there alot faster. You would not only have a tiny bit less rotational mass but the benifit would be greater tourqe to the ground!

 

Lower profile tires maybe, but smaller wheels are bit too impractical because we would have to get smaller brakes.

 

I think this was discussed previously...

something like 225/40's would reduce the gearing by about 6-7%, which would certainly be noticable. The car would need lowered to look good, but all else would be ok.

The speedo would read optomistic, or you would need it recalibrated.

I think in-gear acceleration would certainly be improved.

The gearing change should help the

 

[QUOTE]Originally posted by Scot:
[B]I think this was discussed previously...

something like 225/40's would reduce the gearing by about 6-7%, which would certainly be noticable.

 

[QUOTE]that's what the engineer said: since your tires are rotating faster, the contact patch doesn't have as much time

 

Thank you Bieg for clarifying.

here's one S2K with smaller tires:



It's lowered, doesn't look too bad.