my speedometer is 10 mph higher then actual speed. So when im going 55 on the speedo, i'm actually only going 45. Anyone know how to fix this?

get rims and tires that are equal to the stock diameter.
http://www.miata.net/garage/tirecalc.html
Plug in your stock tire size and try to find one that will be as close as possible.

i have the stock tires on. Winter is coming around.

damn, then I have no clue why it would be so off.

What's your current tire size?

my speedometer is 10 mph higher then actual speed. So when im going 55 on the speedo, i'm actually only going 45. Anyone know how to fix this?

i had a similar problem with the RPMs on my 94 ex coupe, it was reving like at 10, all of a sudden without any mods, i just took the gagecluster apart and tweked the potenciometer to find the correct seting.

I was waiting to confirm this before I posted, sorry it took so long, but there is a speed sensor on the transmission housing that controls your speedo. It's possible that it may be going out. You can replace that part or take your car to a local auto shop and have them check it out to make sure it's good.

i have the stock tire size. i think it's 185/60/14? but the weird part is that right now my speedo is 10 off but when i put my 18's on it seemed like it was like only 6 mph off. Something must be pretty messed up huh?

and i bet that speed sensor is pretty expensive?

If you had a shop install the wheels when they were first put on, I would see if they made an adjustment to the speed sensor to compensate for the wheel size. You can make adjustments but I wouldn't recommend trying it unless you know what your doing.

no, i did it myself, but the speedometer was off when i first bought the car. The stock tires were on and then i put the 18's on and it got better, but then i put the stock tires on and it is still 10 mph off

You need to have a shop check it out. They may be able to adjust it but more than likely they'll have to replace it. That could get you out of a speeding ticket though. Just play it dumb and have it checked after you get the ticket, then go to court and tell them your speedo was off and you got it fixed. If you can show proof then they usually throw it out.

i have yet to get a speeding ticket. lol, i got pulled over for going to slow in the fast lane on a highway

I guess that's how you found out that your speedo was off?

no when i was driving, i noticed that everything seemed extremely slow. Well when i got on the highway i was getting passed by everyone when i was going 80 on my speedo. Well i had a friend drive next to me and he told me what was going on. So thats when i noticed.

the speed sensor cost about 110 to 180 depending on the brand.

Might be the instument cluster too. And are speed sensors really that expensive? I need a new one.

found one at murrays discount auto for 107 but they had to order it.

to much not worth it all i need to know is that im 10 under