2nd Gen Non-Engine/Transmission 265s throwing off odometer?

[NPloysa]

Are 265s any taller than stock 235s or 245s? I know they are wider but how much taller?



I wonder how much they have increased my actual miles?



Thank you.

 

[ata]

265`s are one inch taller then 245`s. your speedometer will be about 3 mph slow at 60 mph. so you will be doing about 63 mph. and your mileage will be 3 miles short every 60 miles. atleast that`s the way mine is. BUT WHAT DO I KNOW?

 

[Tardog]

Tire width is used in the formula of tire diameter. so an increase in width and staying with the same side wall ratio (75, 85) the hieght of the tire will be a direct portion of. An example would be a 245/75 has a sidewall hieght of 75% of 245 millimeters or 183. 7mm where as a 265/75 has a sidewall hieght of 75% of 265mm or 198. 7mm. So tire diameter is 2 x width x sidewall ratio + the rim size. so a 265/75/16 is 2 x 265x. 75 + 406. 4 (metric for 16") = 803. 9mm divide by 25. 4 = 31. 64" this is just theory but this is how it's figured. Correct me if I'm wrong. I have no idea why they mix the imperial and metric with tires.

 

[NPloysa]

So, if you do the math correctly my odo shows 101082 when I really have 99771 miles.



My tires were put on at 75,863. So far my mileage has been off for 26291 miles.



So, every 60 off by 3... 26291/60=437



437x3=1311 miles



101082-1311= 99771 Actual miles?



Right?

 

[ata]

No your mileage is 3 miles short every 60 miles so you would add the 1311. 101082+1311=102393

 

[jrobinson2]

You have it backwards

I think you have 102393. If the tires are larger you go farther for each revolution so your truck has more miles than indicated My speedometer was 2. 5 MPH off at 65 MPH indicated with 265/75/16s

Jared

edit: looks like someone types faster than me.

 

[NPloysa]

Oops, did it the wrong way. Damn, those miles just snuck up on me. Usually just keep it on trip so I can track tank mileage. I bought it at 60,000. Put on 42,000 damn quick!



Nick

 

[klenger]

Here's a gear speed calculator using an Excel spreadsheet that I made.



http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls

 

[Mackie007]

klenger,



Thanks for posting your spreadsheet, that is a very handy tool.



Best Regards,

Mac

 

[wcjp]

When compared with my GPS my speedo is off by 1. 5mph.