Effect of tyre sidewall height on road speed
Turbo Mini Forums

I am trying to decide which final drive for the turbo engine when I build it. I will be aiming for 100 brake horsepower through modest tweeks. (as a starting point)

I can't decide which final drive to go for, I have both. On a 12 inch wheel the 60 profile tyre with a 2.9 fd mangaged 60 at pretty much bang on 3000rpm and the same speedo with a 3.1 fd indicated 60 at 3400rpm

what effect will the lower profile of a yokohama A048 have on the road speed compared to the Falkens with a Higher sidewall?

Is there a formula out there to enable me to work it out?

Cheers
James

Edited by minimole23 on 10th Jan, 2008.

the profile relates to the width of tyre - what sizes are you proposing?

Ahh, My bad.

What I mean, is the difference betwen the lower profile of the yokohama A048, and the Higher sidewall of the budget falkens I had on before.

Edited original post now.

Sorry.

Edited by minimole23 on 10th Jan, 2008.

Still need to know tyre sizes. Can't tell you anything useful without.

The falken tyres are FK-06G 165*6012
The Yokohamas are A048R 165*55*12

Edited by minimole23 on 10th Jan, 2008.

The rolling raduis of the Yokohamas will be slightly less, therefore you will go at a slower road speed for the same revs.

Discount the speedo readings as if you have changed the FD and the tyre size they will be all over the place, best way to check easily is with a sat nav.

your 60 mph will become 58 mph at the same revs ,heres a good clculator for you http://www.tyretraders.com/Tyrecalculator/
regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Thanks for that. Basically its not worth worrying about.

http://www.geocities.com/z_design_studio/t...sion_z28_6.html

handy gear ratio calc

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Interesting, I now know im crossing the line at 6121rpm

The above isnt 100% accurate, as actual tyre sizes in real life arent always 100% true to the quoted dimensions.
Some end up taller, or smaller....and then there is also tyre wear which makes them smaller.

But it is pretty close.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

well i'm going from a 3.9 to a 3.2 so thats a 20% increase. pretty good as i was hitting the limiter @ 7000 at 100mph. it should make all the difference to the 1/4mile times

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

yup

the revs are going to be for the 16v

I was trying to make my own gear calculator and digging through TM for some info on popular tyre circumfrences I found some posts by TD saying that most online calculators work out the tyre circumfrence a bit wrong.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7560

Take that into acount!

interesting post this. i have been wondering about this a bit as i am getting flat out on the 1/4 mile just before i cross the line with a 3:44 diff. was thinking of going up from 10's to 12's to maybe get that bit extra legs. the torque isnt a problem, just the top end a bit. can only max at 89mph!

balls to the blower!!!



1330,stage3 head, gt1549, canems ecu, S/C box and drops

im going across the line at 4950 rpm !!! eek at 96.55 mph . thats on a 2.95 diff and 165/60 12s.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM