I just got a 90 Ranger 2.3 4 spd with OD, 14 inch wheels, P215 70R14 tires. My speedo is off by about 9 mph. speedo reads 53 or 54 , gps says 45, any ideas on how to correct this? Is it possible that this came wit 15 inch wheels and someone went smaller, the wheels are stock ford aluminum wheels.Thanks

 

1994 and earlier Rangers used regular speedometer cable gear setup in transmission or transfer case, so you can just change the Driven Gear to correct speedometer for tire size or axle ratio changes
1995-1997 used the same setup but no speedometer cable.

Look on the drivers door label, backside of door edge, it will show stock tire size, you don't need this to calculate correct speedometer just FYI info
But you will need to know Rear axle Ratio, look here: Ford 7.5 & 8.8 Inch Axle Tag & Door Codes : The Ranger Station

Get the AXLE code and then look up the Ratio

P215 70R14 tires have 26" diameter, 25.9" to be exact

Then go here: Ford Speedometer Gear Calculator

Drive gear is 7 tooth
Ratio ??
Tire diameter 26

That should tell you what Driven gear you need to change to

Follow the speedometer cable to the back of transmission, there will be 1 bolt and a fork holding it to transmission, remove the bolt and pull out the unit, you will see the gear that needs to be changed
1990 will probably also have a VSS(vehicle speed sensor) as part of speedometer cable hookup on transmission, 2 wires, it is used for cruise control and computer info

Units are seen here: Ford Ranger Speedometers - How They Work

 

Thanks, this is the info I needed. Great to be here on Ranger-Forums. My first Ranger and the knowledge here is invaluable.