zainanwar

i have the stock tyres which comes with the auto the 16 inches one. now i have 245 18 inch tyres and i like to know that will this effect the speedometer reading or not. as if the meter is showing 100 than will it be 100 or a little faster than than that. thankx

DarkBrew

As long as your 245-18 has a profile of 40 then the speedo will be within a few percent of correct. What wheels did you get? (width and offset, post pics)
What's your location?

zainanwar

zainanwar

hello anyone?????

CTrx8

iTrader: (2)

you're fine. so you got the 16s originally which means you have an automatic and you're learning to launch against a tibi. your threads get funnier and funnier.

Huey52

iTrader: (2)

16" stock? I didn't know there was such a thing. Anyway, you'd have to a much more dramatic alteration of the diameter of the wheel and the height of the tire to have any notable effect on the speedometer/odometer. As we know, the number after the slash in the tire size schema is the sidewall height; e.g. my stock 225/45ZR18 or potential 245/40ZR18. In my case going from 45 to 40 profile is negligible from a speedometer/odometer perspective.

Going from a 16" wheel to an 18" is of course more significant than altering your tire sidewall height.

With a larger than stock diameter wheel/tire height you will be going slightly faster than your speedomenter reading as you will be covering a slightly greater distance with each revolution (larger circumference). It's a Pi x Diameter thing.

All quite academic and nothing to worry about.

CarAndDriver

Try this online calculator...

http://www.1010tires.com/TireSizeCalculator.asp

zainanwar

the 5mt comes with a 16inch

bulletproof21

not in the U.S. where are you located?

valpac

iTrader: (2)

225/55-16 tire = 653.9mm dia.
225/45-18 tire = 659.7mm dia

< 1% diff in dia. thererfore no diff in speedo readout.

zainanwar

its 245/45-18 not 225/55-16

refugeefrompistons

Huh, first productive topic posted by zainanwar. Good job!

https://www.rx8club.com/rx-8-discussion-3/rx8-vs-hyundai-coupe-help-133824/
https://www.rx8club.com/rx-8-discussion-3/quarter-mile-question-134054/
https://www.rx8club.com/rx-8-discussion-3/short-shifter-134168/
https://www.rx8club.com/rx-8-discussion-3/standard-power-vs-high-power-133878/
https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/0-60mph-times-128629/

valpac

iTrader: (2)

do your own math. oh all right.

245/45-18 = 677.7mm dia vs 653.9mm is approx. 3.5% diff.

go with a 245/40-18 to be closer to stock 225/45-18 tire.

Renesis07

iTrader: (1)

tyre???

zainanwar

thankx guys. actually i love my car very much so i keep on asking stupid questions just to know every little thing abt my car. i am sorry if any of u find my questions stupid.

kersh4w

iTrader: (3)

at least you're learning.

;D

DOMINION

You'll be ok. I have the same set up, 245/45/18 and I have a 04' AT that had 16" wheels.

Razz1

It will be slower as the 18" are much heavier.