Speedometer correction for different sized tires

[General]

Has anyone adjusted their speedometer settings to correct for differently sized tires? My tires are 12% larger diameter than stock, so my speedo reads 12% slower than my actual speed. I've gotten used to it, but I want it fixed. A ton of you out there have different tires, too. It's usually a simple calculation (revs per mile) in the ECU. One of the most reputable Roxor ECU tuning companies says it can't be done (only after I paid them to do it and they mailed back the ECU unchanged, keeping the money). Is it possible? Will someone take my money and fix it?!

 

[BoxRox]

IDK- paid for the same service and speedo is still inaccurate, I think. Noticed it when approaching construction zone where they have speed monitor sign. I’ll check with gps and report back. Had it set for 85s

 

[Eyellgeteven]

Has anyone adjusted their speedometer settings to correct for differently sized tires? My tires are 12% larger diameter than stock, so my speedo reads 12% slower than my actual speed. I've gotten used to it, but I want it fixed. A ton of you out there have different tires, too. It's usually a simple calculation (revs per mile) in the ECU. One of the most reputable Roxor ECU tuning companies says it can't be done (only after I paid them to do it and they mailed back the ECU unchanged, keeping the money). Is it possible? Will someone take my money and fix it?!

How much did they take? I've been wondering about my 235 85s and whether it changed the speedo reading.

 

[Bhayarock]

Has anyone adjusted their speedometer settings to correct for differently sized tires? My tires are 12% larger diameter than stock, so my speedo reads 12% slower than my actual speed. I've gotten used to it, but I want it fixed. A ton of you out there have different tires, too. It's usually a simple calculation (revs per mile) in the ECU. One of the most reputable Roxor ECU tuning companies says it can't be done (only after I paid them to do it and they mailed back the ECU unchanged, keeping the money). Is it possible? Will someone take my money and fix it?!

Idk this video by Diesel freaks shows it can be done

 

[MAGAHAWK]

Has anyone adjusted their speedometer settings to correct for differently sized tires? My tires are 12% larger diameter than stock, so my speedo reads 12% slower than my actual speed. I've gotten used to it, but I want it fixed. A ton of you out there have different tires, too. It's usually a simple calculation (revs per mile) in the ECU. One of the most reputable Roxor ECU tuning companies says it can't be done (only after I paid them to do it and they mailed back the ECU unchanged, keeping the money). Is it possible? Will someone take my money and fix it?!

The company you used doesn't sound very reputable to me. Sounds more like a Rip-off. Why don't you consider posting their name so others can avoid the same scam. They deserve the exposure.

 

[Bister]

How much did they take? I've been wondering about my 235 85s and whether it changed the speedo reading.

Here is a site that you can compare tire sizes on and rev/mile etc. Put the stock tire in "Size 1" and your tires in the other.

Tire Size Comparison

 

[Eyellgeteven]

Thanks for the link!

Looks like there isn't TOO much of a discrepancy...a little less than 5 mph at 50. I can live with that. Then in a couple of years when I have it tuned, I can have it adjusted at the same time.

 

[BoxRox]

Went for a ride with gps. Running 235/85r tires. When speedo reads 50mph, gps says 46/47 mph. The Rox speedo is hard to read accurately because you’re looking down at it.

Anyway, speedo was set by Diesel Freaks. Not too bad, better than before. From Tire Size Compare site, looks like with speedo reading 50, actual would be about 55 with no change to ECM so Freaks obviously reprogrammed.

 

[RoxorFlatFender]

Bringing this back from the dead.

These guys have a plug and play unit. I bought one and it works great. Easy and simple.

Mahindra Roxor Speed Sensor Calibrator/Correction Device | Lutz Auto

 

[GPG]

Wade at diesel freaks is the man! I've talked to him on the phone and really knowledgeable on the Roxor!

 

[jrobz23]

My stock speedo reads fast as well.