Correction for tire/rim sizes? - Fuelly Forums

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Old 10-07-2009, 03:21 AM   #1
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Correction for tire/rim sizes?

Correction for tire/rim sizes?

I know my tires are smaller than factory and it's throwing off my miles a little bit, can we have a feature of being able to fix this? Because using scangauge2 we know the ratio to be adjusted.

can we have a feature to adjust for tire sizes?

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Old 10-07-2009, 03:25 AM   #2
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Sorry neosin, this is a rare case and we've decided not to add features like this that will only affect a small number of users. We have a long laundry list of features to add to the site including better graphing, better reporting, and much more.

Maybe there's a way to adjust your stats as you enter them and make a note of your changes?

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Old 10-09-2009, 08:35 PM   #3
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It's easy enough to approximate the difference (your trip & odometer are hardly precision instruments them selves!). You need to know the % difference between the tyre profiles then apply that to the mileage. A quick n' dirty way is to use the tyre profiles, tread width is divided by the profile as a % then doubled & applied to the wheel diameter. If we take 195/45R15 then we get:

195*0.45*2/25.4+15=21.91" Ø

(the 25.4 is covering millimetres into inches)

Say I'm going to move to 195/40R16 tyres I have the result 22.14"

You then use the two numbers you got to get the difference in %, 1.05% in this case. So I'd add 1.05% to my mileage total.
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Old 10-14-2009, 01:53 AM   #4
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With Scan Gauge you can adust your speed offset when you set it up. You will need GPS and then adjust so that the gauge is reading the correct MPH. I do this in my jetta as it is off just a bit. I then use all the info in Scan Gauge when filling up and inputing it here on Fuley. I am off just a few miles every tankfull with my odometer but Scan Gauge is right! LOL!
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Old 10-19-2009, 05:07 AM   #5
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Thanks guys, I've installed a scangauge2 and did the setup with a GPS, it is off about 4MPH. I do not know yet if the odometer is off yet, i've heard some people on tdiclub say that the speedo is off but the odometer is spot on, I haven't checked that yet.

On my next road trip to dallas (from houston) about 400 miles, I will check odometer/GPS/Scangauge2 and tell you what the diff is. At least in my case and then I'll know what adjustments I should make.

By the way PB, love the site. Can't wait to see better graphs and other fun things.

Here's a thought how about a graph of you and your friends that would be fun...
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