Tire sizing odometer modifier?
 

Adding a percentage modifier to odo readings automatically?

So say you have a car with bigger diameter tires than the car was sold with stock. For example, I have a 205/50/15 tire on one of my cars which was sold with a 185/60/14 wheel from the factory. The overall tire diameter is about 1.5% more than stock. Thus, the vehicle's odometer, being calibrated for the smaller tire, will tell me that I went 1.5% less distance than I actually did.

I understand this is a real simple thing to do with a calculator, but perhaps there is an option to add or subtract a certain percentage of miles from every reading you log on Fuelly. And perhaps a link to a tire size calculator. For some people this can end up being a significant difference and is rarely considered.

My tires make my speedometer off by 7%. I run a Scan Gauge 2 with that percentage programmed in to give me my correct speed. When calculating my tanks for Fuelly, I just add 7% to what my trip meter shows.

Right, I am asking for a way to automatically do that rather than making an extra calculation every time I add a fuel up.

Scan Gauge actually adjusts it. My tiress are stock size but my spedometer and odometer are off a little. You have to get a GPS go down the highway and adjust Scan Gauge MPH to the same as the GPS. Now your Scan Gauge will give you how many miles you actually drove. Over a tank full for me my Odometer says about 4 or 5 miles more than my scangauge. I just use the scangauge number for more accurate numbers. Get one you will like it! LOL!

later

erick

OK, so for those of us without OBDII...

GPS or pad and paper. My old cars I just have to wing it.

Later

Erick

https://miata.net/garage/tirecalc.html

this won't do it automatically, but it's good for quick calculations.

I took the RPM (revs per mile) posted @ Tire Rack for the OE and replacement tires, which amounts to a 3% difference for the taller replacement tires. I multiply the trip meter reading by 1.03 and divide that by gallons used. Sometimes I even do it by long division, it's not that difficult.

That Miata calculator is not accurate. I've run a few calculations with sizes from TR and it doesn't add up. Kinda blew the easy way.

It would be nice if there was a calculator built into the site here, no way to correct for the 1.03% that my different tires contribute to MPG.

well here's another...https://1010tires.com/TireSizeCalculator.asp or this one...https://www.euroshina.com.ua/calc.php...=13&lng=en