--==:: Rim and Tyre Calculator ::==--

[Ben Hewitson]

I though this might be usefull. most people know that say a 185/60/14 tyre and rim package is interchangable with say a /40/16 or /50/15 but what about stretching the tyres accross the rim for that drifter look whilst keeping the profile very low on your oversized rims....? well i have an answer. this gives you overall diameter (good for keeping the speedo accurate) and rim tyre sizes...

Have a play.... It tells us (N12 lads) that the original 185/70/13's have the same rolling circumfrence as a 205/45/16... 1851mm... so the 40 series is actually a bit too small (3% of circumference.. not much but 3% of speedo out is still bad..) so you can stretch a 225/40/16 on it and get the same result... (with a 7" rim say)

http://www.tyremaster.com.au/fitment_tips/diam_calc.htm

[thepurplepulsar]

Here's an even better one:

http://www.roversd1.nl/sd1web/wheelcalc.html

You can put in your gear/ final drive ratio, rpm and wheel combo and it gives you what KPH/ MPH you would be doing etc...


I was playing with it last night trying to work out what sized street tyre I'm going to use next at the drags. Since I've put 65 profile rubber on my car, I've been having to change into 4th just before the 1/4 mile line.

Here's what I worked out:

Previous tyres: 185/ 70/ 14
Line: 3rd gear, 6700 rpm @ 105mph.

Current tyres: 185/ 65/ 14
Line: 4th gear, 4850 rpm @ 105mph

Think I'll go back up to the higher profile so I can stay in third, cross the line and hope to be doing about 7200 rpm which should be about 113 mph... that's if it works out that way.

[Ben Hewitson]

Touche`.. yours is better...

[shanec86]

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

this one looks prettyer