low profile tyres

[dub_addicted]

does anyone know how badly it will effect my speedometer if i have 18s on really low profile such as 225/30/r18? for an example

[tinman]

C=2piR=piD if memory serves me correctly

tape measure time, take the standard wheels and measure the diameter inc tyre. call the measurement you get X.

then do same for the new wheels and tyres. call the measurement you get Y.

then do a quick X/Y and then -1, and times by 100.

the output is the percentage difference of the old vs new tyres. and in reality, considering the Mk2 has a guessometer as a speedo, it'll probably make your speedo more accurate.

[Overseer]

use this  >>> http://www.miata.net/garage/tirecalc.html

[VeeDubGTI16v]

yeah when i do a 0-60 with the g-tech it always says about 65/67mph ish on the clocks when it gets to the real 60.

[tinman]

not clocks - guessometer.

my guessometer says 120 at 110. it stays on 120 until its actually 120, at which point it reverts to being a fairly accurate speedo, at that point it stays accurate all the way through to the point where i run out of nerve...

(its not nerve from high speed though - its the dreaded thought that if the engine at this speed lets go i have a 2k bill on my lap for a new block and rebuild)

[dub_addicted]

thanks everyone im thinking of  getting 225/30/18s for the mk4  after the current ones wear out, should look great on the rims 

[free]

my mate who has mark 2 broke down last nite, n he has 17's ?n i towed him home and this poped in my head as i was towin him so i cumunicated with him (dident ring him cos that would of been norty lol) n asked him what speed his speedo said n it was the same as mine, on 14s, with 60 profile

[Overseer]

well of course.. if the tyres are right.. the rolling radius is perfect.. its only when u deviate you'll have problems

[richy]

225/40/18s will give you the same rolling radius as stock.