I was thinking about this earlier as I am due to get some Winter tires for my car and I was checking tire sizes on the miata comparison.

By my numbers, the stock sizes for both models are 175 65R14 Base and 195 55R15 Sport. This means the Sport tires are 2.1% slower than the Base tires due to a larger circumference (73.7 vs 72.1 inches). What I was wondering.... does Honda actually reconfigure the speedometers on both models to match their 'stock' tire sizes? Or do you think it is more likely they are simply making the one configuration and allowing for the 2% difference to stand?

It does seem nitpicky but I want to make sure I pick a winter tire thats within a certain percentage.

For example if the sport model tires are the proper size then I need to put 185/65R14 on my car for winter. If the base tires are the proper setting for the speedometer then I need to get 195/60R14s.

Anyways wanted to throw this out and see if anyone had some thoughts.

 

I have the sport with stock sport wheels and tires. The speedometer reads maybe 2% fast compared to a gps reading. So when the gps says I'm traveling a steady 60 mph, my speedo shows 61. That's about the most accurate speedo I've every had.
You really don't want it reading too slow or you're more likely to get a speeding ticket.
Don't sweat 2%!

 

I have a Sport. I checked my odo and speedo using the mile markers on the highway and found them to be quite accurate. For winters, I'm going to put on 175/70-14 instead of 175/65-14 because the circumference is a closer match.

 

don't worry too much because no in-car speedo is ever very accurate.