I have a friend that has a F-150 1998 4.6 5 Sp. he has 265x70x16 tires in which is a little taller than the tires that came on truck and he speedometer is off 5 miles per hour. What can he do to fix that and make it right??? the truck came with 255x 70x 16 need help with this one guys thank you

 

harry,
He's in luck. For '98 only, there is a Power Programmer (forget the brand name, but I think you can find it elsewhere on this site) that allows you to re-program various characteristics of the truck. One of these is a change in wheel diameter and/or gear ratio. This is like a Superchip except that you can make changes at any time just by plugging it into the diagnostic port. I believe you can change the shift program (useless to your friend), A/F ratio, ignition timing, etc. I also think it will eliminate the top end cutoff (~95 mph/~5500 rpm). I think it sells for around $300. The brand may be Hypertech.

 

I would tell you friend not to worry about it. The differece in those tire diameters will only throw the speedo off about 1%. According to Mike Troyer in the chips forum, the Ford speedo already has something like a 3% accuracy anyway. Lots of people (including myself) go from 265/75-16's to 285/75-16's with no problems, and it's a larger difference than your friend's. My speedo is about 2mph different @ 70 mph on the highway with the new tires. The only way your friend's speed would be 5mph off is if he's driving extremely fast (i.e. 500mph) or the original tires that came w/ the truck were not the 255's.

------------------
From factory:
2001 White 4x4 SuperCrew (Lariat), 5.4L, limited slip, skid plates, towing pkg, captains chairs, CD changer

Add-on's:
SuperChip; Black Westin Nerf Bars; Husky Mud Guards (F&R); Beige CatchAll's (F&R); Line-X bedliner; Eagle 121-series 16x8 polished wheels w/ American Racing centercaps; 285/75-16 BFG AT-KO tires

Plans:
Intake; Exhaust; Shocks

[This message has been edited by ChrisS (edited 05-24-2001).]

 

Would having oversized tires cause the transmission to bump into second gear after driving a distance on the highway. After I drive on the highway it bumps into second gear and slams into reverse. This happens for about two days of driving in the city and then it is back to normal. I have a 94 F150 4X4 E4OD. What would I need to do to change this. I don't think the tires are that much over stock tires.

Thanks, Joe

------------------
1994 Ford F-150 4X4 XLT V8 5.0, AC, PS, PW, PL, Tilt Wheel, Cruise, AM/FM Stereo Cassette, ABS, Bed Liner, Optional Fuel Tank, Towing Pkg, Green/Beige Two-Tone Paint, Premium Wheels