Changing Tyre Diameter & Adjusting the Speedo

Hi All,

I'm looking at changing the tyres on my 65 Baja from 14" to 15", and was wondering how much of an issue I would have with adjusting the speedometer to compensate?

Do-able at home?

Cheers,

S

it would have been 15" tyres to start with when a standard beetle,so maybe your speedo has read wrong all the time❓

Depends on the diametre of the new tyres, you can work out the change in the speedo reading by compairing the diametre of the new and old tyres , you can then take the speedo to a instument repair shop and they can recalibrate it to suit.

The rim size is irrelevant, the important thing is the overall diameter of your tyres. What tyre size are you planning on using? The stock tyres were something like 155/80R15, so if you're upgrading to a 195mm section width, then 195/65R15 will get you pretty much spot on. http://www.willtheyfit.com/ is a good calculator to use.

zeroktrian wrote:Hi All,

I'm looking at changing the tyres on my 65 Baja from 14" to 15", and was wondering how much of an issue I would have with adjusting the speedometer to compensate?

Do-able at home?

Cheers,

S

Hi

The speedo is non adjustable to the home mechanic....

so, tyre sizes are the easiest way to go....

although the tyres needed to set the speedo correct may be expensive.... $$

cheers

LEE

Hey All,

Cheers for the comments. I'm currently running 205/65/R14 tyres at what I believe to be a correct/accurate speedo reading. So presumably from what has previously been said I can use this (and potentially rim-size?) to figure out what tyre I can "transfer to" to 'keep the speedo happy'?

Cheers,

S

from memory the closest tires size to stock is 205/65/15. so with what your saying your actually undersize by about 80 odd mm in the rolling diameter with the 14 inch rims
try playing here and remember that the stock tire size was originally 165/100/r15
http://www.miata.net/garage/tirecalc.html