i have a 2004 ram 2500 and i recently put new 285/70-17 tires on.will these throw my speedo off any and if so how much?

 

Here is a calculator for you. It's kind of complicated but it works. http://www.csgnetwork.com/tireinfo4calc.html

 

thanks kevin,very helpful.

 

when i upgraded from stock 16" tires and wheels to '04 stock 17" tires and wheels i checked the accuracy of my speedo and found it was almost right on, so you won't be off enough to worry about

 

Find a cop running a radar trap and go past him at exactly 30 over the limit. Use math and the speed written on the ticket to calculate the percentage error of your speedo.

 

excellent idea,i will call you from jail tomorrow

 

I run 35" tires, I found that my speedo reads 10 to 15 kmph low.(always wondered why I get the eyeball from cops when speedo was bang on) ran a handheld gps on the highway to find the exact differences which are different at different speeds