i just got a 6 1/2 inch fabtech lift and 35 in bfg muds on my 98 extended cab. currently i do not have new gears. my question is if i dont put new gears on, will my mileage say my truck has more miles than i actullay put on it because of the bigger tires or anything? for example if i go 20 miles will it say i have gone 25. thanks

 

The taller the new tire is from stock, the slower your speedo and odometer will read. For example, I have 265/75/16 on mine from a stock 255/70/16. Really only an inch or two difference, but when my speedo said 60, I was really going 64. When the odometer showed twenty miles, I had really traveled 21 miles. So you will be putting less miles on the odometer then you really travel. Your rear end ratio should be changed to something like a 4.10 or 4.56 so you can still "get out of the hole" quicker, without lugging the engine and tranny. Decide on the rear end gears first, before you change the speedo gear so you get the correct one. That all depends on the rear gear.

I changed my speedo gear from a 20 tooth to a 19 tooth. Now my speedo and odometer is much closer to reality. Still just a touch off, but no more adjustment available. I now have to go 100 miles to get the one mile difference. Hope this makes sense. I kinda rambled there at the end.......

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1997 F150 4x4 Off Road, SuperCab, Short Box, 5.4, Royal Blue/Silver, K&N, Gibson SS, LT265/75/16 Wild Country APT's