question:

would reducing the stock tire diameter on the drive wheels "effectively" provide higher gearing?? in every gear?? if so, is there a calculation/equation for this "phenomenon"?? and if so, what would be the equivalent/appropriate required tire diameter to replicate the effect of a 4.44 gearset??

(we "know" that an OE S0-2 in 225/50/16 is "effectively" sized as a 245/45/16 - this would be used as the "baseline") .

thanks all........

side note: i realize that if one were to make the requisite diameter changes, there would be speedo and mileage accumulation implications.........the extent of which, i am unclear on.

 

Reducing rolling diameter (tires diameter) will have the effect of higher multiplication of your available engine torque. It will be like having a shorter final drive installed, you will reach the top of each gear quicker but each gear will be shorter meaning instead of reacing XX mph in 1st you will reach XX - difference change makes.

So, it basically shortens your overall gearing. It should have a positive effect on the acelleration of the s2000. However, unless you make a drastic change, the difference will be almost negligible.

Calculation is: (Gear multiplier X Final Drive X Gear Reducer) / (tire radius in feet)

You can also calculate the difference it will have on your speedometer and odometer. Just calculate the circumference of both tires and the percentange change between them will be the change on your speedo/odo...

As for the changes needed to reproduce the effect of a 4.44:1, you are looking at a reduction of about 8%.

I estimate that you will need to go down to a 225/40/16 to have about a 7% reduction, so almost the same as 4.44:1 FD.

It's morning, I hope I didn't write anything stupid.

 

Sev covered most everything.

Here is a site that tells you what % off you make the speedo(and will also give you the % of acceleration increase).

http://www.miata.net/garage/tirecalc.html

I have the J's racing 4.44 gearing and it is an 8% difference. To get that 8% if you were running 245/40/17 tires you would need to run 245/30/17 to give you 7.8%

You would sacrifice sidewall flex(which is better for launching) and you would risk rim damage on a pot hole, and also have a stiffer ride.

Note: I used 17" wheels because the oem 225 16" tire is more like a 245 and it would make it more complicated to explain. But if we took a "normal" 225/50/16 tire running 245/35/16 would give you 8.5% and you would have a slightly larger sidewall than the 17" setup.

 

I have the time today so "what the heck".

Here are the exact calculations for you (calcs done at first gear I believe 3.13 multiplier and at peak torque of 153 lbs/feet):

Stock with 225/50/16 >>> (153 x 3.13 x 1.16 x 4.11)/ 1.05 = 2174 pounds of thrust


4.44:1 final drive change stock tires >>>>>> (153 x 3.13 x 1.16 x 4.44)/ 1.05 = 2349 pounds of thrust

So a difference of about 8% as posted above

If we now use a smaller diameter tire

Stock drivetrain and 225/40/16 (153 x 3.13 x 1.16 x 4.11) / 0.977 = 2337 pounds

So a 7.5% change over stock.

225/40/16 is not really a feasible solution if you ask me, It will look like crap for one thing (lots of wheel gap)...

There you go.

 

try KUHMO 712 ecstas. i ran the 225/40 in rear with 215/40 fronts
hey are cheap($85) and reduces stock rid height over 1 inch and make the stock rims look fantastic due to the lo profile appearance.....and yes, thats why i did it,,,for the shorter final drive...its great. the car will be very low...

 

[QUOTE]Originally posted by Jenner
[B]

Note: I used 17" wheels because the oem 225 16" tire is more like a 245 and it would make it more complicated to explain.

 

it actually looks GREAT...the tiny wheels have a very purposeful look and the car is lowered. yeah, there is a bigger gap...and its cool. i have pics somewhere....try to post.

 

[QUOTE]Originally posted by sfphinkterMC
[B]it actually looks GREAT...the tiny wheels have a very purposeful look and the car is lowered.

 

Since diameter and circumference are related directly, you don't need to convert - use diameter which is always in the specs.

 

convert what?