If I upsize my wheels can I get my speedometer reset to match the bigger wheels?

 

The speedometer is mechanically controlled by a gear + sensor in the transmission. You'd have to find a replacement for that sensor, and I doubt there's one out there. Only thing you can really do is have your speedometer checked (use mile markers) and figure out how much of a variance there is, and keep that in mind when driving.

 

http://www.miata.net/garage/tirecalc.html
i hope this might you guys. make sure to update ur java or else u can't view that calculator.

 

The speed sensor looks a LOT like the one from 95+ Eclipses (90-94 used a cable instead of an electronic sensor), and some Eclipses came with 17"s or 18"s stock. Try one of those, or just go ask the dealer. They *might* know, but I kinda doubt it.

This is definitely the cheapest way to go. It'll only be a few percent anyway, so if the speedometer says 50, you're going 52-53.

 

it's actually not more that a couple miles off when at 70. go to www.tire.com and go the info center. you can put in current tire size and size you're going to and find the difference

 

If you are going bigger wheels you should be going lower profile anyway. Try and find a close aspect ratio and use those tires with your bigger wheels. No matter what your speedometer will not be 100% accurate, but if you match the outer diameter of your new tires with that of your old tires you should be able to keep it pretty close to what it is stock. 205/50/R16 is about equal with 225/40/R17. Bigger rim, more contact, less roll on cornering, same speedometer readings. Play with the calculators to find something around what you want.

 

One other thing worth pointing out, even with stock wheels/tires, the speedometer is not completely accurate. For example, at 70mph on the speedometer, there's a variance allowed of around +/- 4 mph. The faster you go, the greater the acceptable amount of variance.

 

like any car, Honda actually told my GF that 10% was their allowance. What a croc.

 

For the sake of discussion would these points not be somewhat accurate.

1) even with stock tire size, if coming with 10/32” (approximate) tread dept, as the tire wears down the tread dept deceases so would the overall O.D. of the tire.
2) With under / over inflation the tire changes on the O.D.

Wouldn't these affect the speedometer reading even if using the stock 205-50-16 tires?

Around here the cops like to set up there traveling radar units to make sure we all know our true speed (kind of a warning). I like to use them to check the calibration of my speedometer. snowey1

 

You are correct, tire wear and pressure do affect speedo accuracy.

 

did you know by getting bigger wheels or tires it voids your warrenty cause it will make the oddometer not track properly

 

interesting. Personal experience?

 

Sounds like more warranty fear mongering to me.

 

Someone here had most of his front passanger suspension give out on him and it wasn't covered due to his aftermarket wheels. I don't know if they were equal to stock diameter.