I recently upgraded the stock stock 16's with 17's on my CL-P. They stand about 3/4 inch taller and make for about a 2 or 3 mile per hour error on the speedo. I went to my dealer and he told me ther was no way to correct the error.

I think that is B.S. I worked at a Ford dealer a few years back and I remember that on one for the computer diagnostic systems, there was a specific question that asked for the tire size and corrected the ssytem for the different size tires.

Has anyone had their car back to the dealer and had them recalibrate the system?

 

I don’t think that can be calibrated, but I’m not sure.

Why don’t you size the 17” rubber on the new wheels to be the same outside diameter of the stock 16’s?
That way it will not affect anything.

Shawn S

 

I agree, size the 17's properly, which should have been done in the first place and you won't end up with these issues.

 

I'mma ask the dealer tomorrow if they'll do it and how mcuh it costs.

 

I don't think it can be done. Isn't this all controlled by the ECU? And wouldn't altering the speedo fuctionality be considered fraud?

 

does it really matter if you're goin 40 or 42?

 

I replaced the stock 16's with the stocl size 17's and there is a difference in the overall circumference.

If you have a truck and put oversized tires on it, you can go and buy one of those aftermarket ECU programmers. They are about 200 or 300 bucks. Made by Superchips or Hypertech and other chip companines. Lets you change the shift points, what octane you are running, etc. They let you remove the Rev limiter and speed limiter. And there is a screen of tire size changes. I did it to my Ford Ranger a few years back.

I just cant find any for Acura. So they are out there.

 

If it can be done, the ECU would need to be reprogrammed, & no dealer I know will do that. An aftermarker ECU programmer like stated above will be needed. Maybe call Hondadata & see if they can do it.

 

???

so...get the same size tire for 17s?

 

I went from a 205/55/16 to a 215/50/17. One comes on the CL-P and the other on the CL-S.

The stock 16 at 55 mph (I think) was 844 RPM
The stock size 17's have at 55 mph 821 RPM

There is a difference from the stock 16 to the stock 17.


So wait....now I am confused. Am I actually showing a slower speed than I am really going or is my speedo showing a faster speed than I am really doing???

So the speedo says 60 mph. What am I really doing?

 

http://www.miata.net/garage/tirecalc.html

 

To avoid speedometer error, the overall diameter of the wheel must be the same as the original. A 225/45/17 (25.0) is virtually the same as a 205/55/16 (24.9).

With your 215/50/17's, your speedometer will read 2.4% slow. i.e. When your speedo reads 60 mph, you will actually be going
61.4 mph. OTOH, with 225/45/17's, your speedo will be a negligible 0.4 % slow - an indicated 60 mph will actually be 60.2 mph.

 

slap 225/45/17's on ur car and you'll speedo is gonna be as close it can possibly come to stock on 17's

 

Stock CLP tires are 205/60/16 which are about 25.8 inches tall depending on the brand of tire. The CLS tires at 215/50/17 are 25.5 inches tall. This is a negligible difference and I'm sure the speedo calibration is the same for the 2 cars. Were the 205/55/16 tires original or just what you had on the car previously?

 

If the stock tires on the CL-P are 205/60/16 rather than 205/55/16, then with 215/50/17's your speedometer will read 0.9 % fast. i.e. When your speedo reads 60 mph, you will only be going 59.5 mph, hardly a significant difference.

 

Ahhh, I see.. Thanks for the input guys..

 

iono that sucks

 

You can't on the CL/TL, but you can on the RL . . . I guess Acura thought more people would mod their RLs

Check your RPM spec for each tire . . it's measured in revolutions @40MPH I think.

For example: My TLS OEMs are 819 RPM and the Toyo T 1-S are 828 . . being a smaller tire. The OD spec is 25.5" vs 25.1". I can't even tell a difference and using those speed check radar devices police set up and my readings are right on. So little or no difference.

I would guess you could change it by 18-20 RPM and not have a big enough impact to worry about it. Just watch the school zones of you make a big change . . . they offer no mercy for even 1-2MPH over. :P

Ruf