Alright I know when I had my 32's bfg a/t's on I was going 5mph over what my speedometer read.but now that I got my 35's does anyone know how off it will be...?

 

why would it be off?

 

idk my friend was driving beside me and I askd wat he was going and he was going 5 over wat It showed on mine and he said it was because of my bigger tires probably the gears in the speedometer

 

bigger tires or smaller tires will trow you speed off. Because it takes more or less revolutions to go a mile.

 

get a new speedo gear to compensate for the 35's.

 

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

neat little tire calculator

I would just get a portable GPS, those usually tell what MPH you are going, plus then you have a gps too!!!!

 

Yeah I have crappy little tires on my '99 sport and the speedometer reads 5 mph over my actual speed. It is a nice little ticket prevention system though!

 

mines off by 20kph.

if it says 80, i'm doin 100

i just use my gps for actual speed. i don't even look at the speedo anymore.

but yeah, you can just get a new speedo gear. i think 35 tooth for stock 3.55 gears and 35 inch tires. if i recall....