Going from 265's to 285's, will it affect my speedo? same rim size and 70 size.

Thanks
Chris

 

yeah, maybe 4 mph off. Not that bad I think the tire rack has a calculator on their site to figure exactly I went from 255's to 295 and mine is off 4 mph at 55 mph

 

Do you have the link on tire rack?

 

You are basically going from a 32 inch tall tire to a 33 inch tall tire, so I think it will only be off a couple MPH.

 

It is a percentage, not fixed mph off. You are going 3.5" larger than stock, so your speedometer will read 3.5% slower than you are actualy going. At 50mph, less than 2mph off. At 80mph indicated, you're actually going 82.8mph. Now, most speedometers are off in the display compared to a GPS for example. Bottom line, <5% shouldn't be a problem.

 

http://www.miata.net/garage/tirecalc.html

Were 265s your stock tire size?

 

yes they were 265's