This is the least of my worries now but am considering it. I have the late availability 1998 14" clear coated aluminum wheels on my 98 XLT and I'm wanting to swap to the chrome 15" Splash wheels. I'm wondering if it will make a noticeable difference in the speedometer reading since it's computer controlled, no cable. It's funny that there wasn't a Splash suspension for 1998 except the addition of the 15" wheels and a rear sway bar. All the spindles, control arms, hangers, springs all share the same part numbers. Maybe some had HD shocks but I can't find anything about the suspension being lowered like earlier years. I believe I read in the earlier years of the Splash the front or rear or both were dropped a little compared to a base Ranger. I've already added the rear sway bar from a Splash extended cab on mine.

 

Speedometer calibration will be a function of the circumference of the outside diameter of the tire, not the the wheel size.

 

i went from the standard 14 inch wheels to 235-70-15s I think they are and the difference was negligible. I even went to ford and bought the replacement spedo drive gear (mine is a 94) and it made the readings worse. 2 things you can do. Manually calibrate your number by driving at 60 miles/hr on a straight road if possible and then figure out how much the spedo and mileage is off. There are calibration sites on the net to look at. 2d get a gps/navigator and drive with it for a while and see how far off it is. Mine turned out to be off on the odometer about 4 miles/hundred driven so when I refuel I have to add that to
the total for mpg. speed is less than 2

 

I find that if your speedometer is off, the faster you drive the worse it gets.