prob a stupid question

[antmoneygtz]

sup guyz... this mite be a really stupid question but im gonna check wit u guyz jus to be a hundred percent sure... i heard from a friend that if i switch fomr 16 inch rims to 18 like the ones i bought i may need to recalibrate something involving my mph guage.. . is this true???

[burthold]

There will be a very small change in your spedomitor reading. You also may want to talk with the place you are getting your tires and rims at. Mine is a little on the fast side i.e. when it reads 70 I'm really going between 69 and 70 minor minor change.

Wes

[peanotation]

yeah, since the bigger the wheels, the faster they have to move to complete a circle in the same amount of time. my friend got 19s on his bmw (he had 15) and now when he's going 100 it reads he's going 104. very very very small difference, unless u travel at 200mph all the time, then it'd be like 10 mph off

[mrjaydeeone]

well I don't think theres much of a problem wit my car...I went from 15s to 18s....
I've only heard of the speed being off a lot is if you change the size completely...like if you get 18s and big tires. rather then low profile
if that makes any sense

[Ghost Beat]

it happends more to some than others i have 18's on mine and didnt realy notice much of a diff i go past the speed meter's on the side of the road once in a while and they read the exact same speed im going

[NRG]

It shouldn't be far off because most of us stay within the factory spec. Another words, our overall diameter with tires is equal......

[TJC]

Here's a link found from PinoyESV6 a while back for calculating the differences between different size tires.
http://www.miata.net/garage/tirecalc.html

[pinoyesv6]

yea if you try to keep that ratio really close then u got no problem. use that link that tjc posted. if you keep the ratios the same then u should be really close. i mean ur speedo isn't 100% accurate from the start since the tread of ur tires are constantly decreasing but 1-2 mph difference u wouldn't see til u got to the higher speeds anyways

[antmoneygtz]

thanx alot guyz uve ben a big help

[MysteryGalant]

The tire size sould be 225/40/18 that will keep everything the same