How Do I Set My Speedometer With My Rims/Tires!?

[cWs306]

Hello. My questions pretty much the title.. what do i do to set my speedometer with my rims And Tires so its not thrown off.? Thanks for the help!

[wytbishop]

The speedometer is not adjustable. There are aftermarket speedometers you can buy that use a wheel speed sensor which are, but you cannot adjust the stock speedo.

[cWs306]

ohhh okayy. well thats right on then. i wanted new gauges anyways haha thanks alot.. any suggestions on where i should buy new gauges?

[harthadavis]

Well technically if you can find the same tires the same height that taking off because it is the same. An integral part of your question is, which is a measure of tire old and what is the tire size again? I can tell you exactly what it is off.

[wytbishop]

ummm...what?

[RS_OBD'oh_2]

what rim and tire profile did you put on? I would not clutter the dash with crap gauges.

[umcamara]

I thought you could add shims to the speedometer sensor on the tranny... No?

[Daninski]

Yes, if you can find the same tires the same height that taking off because it is the same then that's the best way to see it because see that they're the same is like it still the same reading no matter how fast your going.

I didn't know about the shimming. Is that in the manuals?

[umcamara]

Yes, if you can find the same tires the same height that taking off because it is the same then that's the best way to see it because see that they're the same is like it still the same reading no matter how fast your going.

Thanks for clearing that up Dan and harthadavis...

I didn't know about the shimming. Is that in the manuals?

I remember reading about shimming the speedometer sensor in a worklog years ago. Now that I've thought about it, I think the shim was for using a mechanical speedometer sensor in a transmission designed for an electronic speedometer sensor....

[wytbishop]

The mechanical speedometer in our cars is a driven by a set of gears. The only way to change the speed at which the speedo cable turns is to change the gear ratio of the gear set. Unfortunately I don't believe that's an option for us. Other companies like Dodge and Chevy offer several different drive gears so that different tire/wheel combinations can be used and the speedo can be corrected, but not Mazda.

Your only option is an aftermarket electronic gauge.

...or do what Dan said...that also makes a lot of sense.

[umcamara]

...or do what Dan said...that also makes a lot of sense.

I actually laughed out loud at work... Thanks for that!

[Daninski]

[wytbishop]

Or...I guess what most people do in this situation is just calculate the % difference in wheel size and just know that your speedometer reads x% faster or slower.

If your overall wheel diameter is 5% larger your speed will be 5% faster than indicated. IF your overall wheel diameter is 5% smaller your speed will be 5% slower than indicated.

[diezzel]

What size of rim and rubber do you have on now?You can up one or two sizes and go to a lower profile tire and it will not change you speedo.There is an easy way,go to a tire shop and ask them or google tire sizes for your car.I have 17s on mine with 45 series rubber.No problem. Then again I could be blowing smoke out of my a__.

[cWs306]

i ended up just saying piss on the rims.. and just kept the stock ones and put some wicked nice rubber on.. seems to work pretty well for me.. can hit round abouts at 95-105 now depending how much i feel like pushing it... stock everything accept for tires hahaha. sorry for any inconvenience i may have caused. but i did learn alot from all this thanks!!