Speed correction

[JC'sGT5.0]

I have the 19" PP rims and hope to upgrade to some 20" rims soon. Will there be the speedometer be incorrect with the new 20" rims and tires? I realize that the just because the 20's are larger the profile can help keep the overall diameter somewhat close.

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[C Cubed]

Go to Tirerack.com and look at the specs. The diameter is what you're looking for. They also give revs per mile. Happy huntin'.

 

[Falconetti]

yes just as stated above, tire rack or just go into a discount tire or any good shop and they can fit you with a tire that is the same height by as you already know having a low aspect ratio or "profile".

If you really want to be exact measure your tires on the tread all the way around, usually in inches is easiest for me. take the inches and then divide them into a mile. if you're in inches you'll want to convert the mile to inches. so 1mile= 5280ft=63360 inches. divide the inches around your tire is into the inches per mile and you will have your revolutions per mile. if the tires are the same or very close the speedo will remain unchanged.

 

[Masorcas]

Go to miata tire size calculator.com and you can imput your old tire specs and new specs and it tells u exactly how much you will be off

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