my tires are 205/55/16 with total outer tire diameter of 24 inches. and i want to use thinner tire for the looks. but my friend told me that if i change my tire with the lower one using the same 16 dia. rims it effect my speedometer accuracy.

the question was what size of tires and rim should i combine to maintain the 24 inches outer diameter of the tire.

please help...

 

Hi there, What vehicle have you got ? Your friend is right on mazda 3 you must inform the I.C that you are replacing the wheels with a different size , i think if you want to maintain the correct size then dont deviate from 205/55R16 . Doing so will have an effect on the speedo reading thats for sure.

 

What do you mean by 'thinner' tires? Do you mean that you want a more narrow tire? If so, then you can get a different size tire that has the same circumference/height of the wider tire that you are now running. You will also have less tire patch contacting the road surface and, therefore, less friction for steering and stopping.

If it is a lower 'profile' tire that you want, then your only option is to use a larger wheel in order to maintain the same tire/wheel circumference. This is what affects the accuracy of your speedometer.

 

Your actual tire diameter is 24.8-25 inches depending on the tire, this is according to Toyo Tires website.
So far I have found nothing that is the same height in a narrower tire, but then again, putting a narrower tire on will affect the handling and stability of the car overall.

 

I'm sure you mean a lower profile tire... one w/a shorter sidewall.
Any OE size will work and get you close. The OE 17" is 205/50. Go with at least a 7" wide wheel and use 225/45-17 and that will get you even closer.
In 18", a 235/35. A little shorter, but closer than a 235/40 (a little taller) which will also work well using an 18" sized wheel.

There will always be a slight deviation from the exact "math" from tire size to size. Also from brand to brand in the same size tire, but these sizes will get you so close you shouldn't have to worry about speedo error.

 

I correct myself , its only if he wants to adjust the overall radius of the tyre , changing the load / speed rating of the tyre wont make any difference to the I.C just the Radius size. If he wants bigger wheels then he will have to change his I.C settings. It all corresponds with the D.S.C / A.B.S Hu/Cm.

 

I better tried 235-35-18. I'll send you a picture as long as i install them. Thanks virg... I really appreciate...

Wow! How i wonder how it look like...