Speedo Correction for Oversize Tires

[Buddywh2]

Looking for tires and I like the idea of something a little bit taller than the stock 225-65's. 225-70 if I can find something, 235-70 if not.
The wheel-wells can certainly accommodate even the 235's but either way the speedo' and odo' will be off: does anybody know if there is a way to easily calibrate out the error?

If not by me using some semi-hidden codes, can I expect a dealership to be cooperative about this and how much should I expect to be charged?

Thanks in advance for any helpful responses I get!

 

[MikeM.]

Looking for tires and I like the idea of something a little bit taller than the stock 225-65's. 225-70 if I can find something, 235-70 if not.
The wheel-wells can certainly accommodate even the 235's but either way the speedo' and odo' will be off: does anybody know if there is a way to easily calibrate out the error?

The Speedo can be calibrated via software if you have the proper equipment/codes. But that's not the biggest problem with increasing tire diameter. This will gear the vehicle taller which is not desirable on a vehicle already geared for economy.

 

[Buddywh2]

In other words you (nor anyone else, apparently) have any idea if dealers will be cooperative, how much it should cost nor about semi-hidden codes so that an owner could do it.

 

[inlinev]

Have you tried asking a dealer? Perhaps you could help out the forum by providing the answer.

 

[Buddywh2]

Have you tried asking a dealer? Perhaps you could help out the forum by providing the answer.

Yeah, I've considered that. But thing is, dealers are a balky lot: they really prefer taking work that falls in line with the usual types of things they do and know about; you know, in their comfort zone.

Bring something novel and they tend to just dismiss your request as somehow invalid (like that Mike M guy does so often), feign ignorance (which may actually be true) or gouge like crazy on the price. So showing up with a little knowledge in these cases can be helpful: like prompting them with the system/tool to use and settings to change and expectation on price based on what others have paid.

What would have been really cool discovering an undocumented way for owners to do it, but I really considered that an outside chance anyway.

 

[MikeM.]

Bring something novel and they tend to just dismiss your request as somehow invalid (like that Mike M guy does so often), feign ignorance (which may actually be true) or gouge like crazy on the price.

I was trying to be helpful and share what I know you ungrateful whiner! I'm not sure how you interpret that as me dismissing your request as invalid??

 

[gimor]

Plug in your tire numbers at url below and it will tell you the amount of speedo error and then some.
http://www.rimsntires.com/specspro.jsp

FWIW I have a Speedohealer on my 07 V-Star that works nicely.
Maybe somebody makes something similar for autos.

either way the speedo' and odo' will be off: does anybody know if there is a way to easily calibrate out the error?

 

[dergibog]

Keep us posted on your experience. Interested to see if the dealer will be helpful. Good luck.

 

[Buddywh2]

I was trying to be helpful and share what I know you ungrateful whiner! I'm not sure how you interpret that as me dismissing your request as invalid??

That's easy... share without the value judgment: "....will gear the vehicle taller which is not desirable on a vehicle already geared for economy. "

 

[Buddywh2]

Plug in your tire numbers at url below and it will tell you the amount of speedo error and then some.
http://www.rimsntires.com/specspro.jsp

FWIW I have a Speedohealer on my 07 V-Star that works nicely.
Maybe somebody makes something similar for autos.

I think I shall resign myself to using my GPS as speedometer. But the 'real-time' mpg guesstimator will be even further off (although as a nag it's still useful I suppose) and the odometer will never tally correctly. Oh well.

 

[Srad600]

Hypertech has a speedometer healer, you'd need to check with them to see if they support the CX-5 though.
http://www.hypertech-inc.com/products-speedometer-calibrator.aspx

 

[Buddywh2]

Hypertech has a speedometer healer...

At first read it looks compelling; but like you say nothing on their site suggests Mazdas after 2013, and no CX5's, are supported. Maybe a phone call will clear it up.

Thanks

 

[CARiD]

You are talking about 17" rims right?

If so I used the speedometer error calculator that I found on the internet and it shows the following:

IMO the error is not that big, so I wouldn't really bother to calibrate the speedometer, especially for winter time only.
Just keep the speed 2 MP/H lower and save a couple of hundreds on other goodies for your car.
My summer wheels are slightly bigger than factory spec tires, and there was a similar error, but it didn't bother me at all.

GPS speedometer will do the job too