[jmczzz]

I found this while searching the web for escort wheel info.
( I could not determine to what the MM measurement refers.)
http://www.vehicle-bolt-pattern.com/for ... guide.html
wheel size bolt pattern lug size MM offset *
ESCORT 81-90 13 X 5.5 4X108 12mmX1.5 63.6 H

ESCORT LX, WAGON 91-94 13 X 5.5 4X100 12mmX1.5 54.1 H

ESCORT GT 91-96 15 X 6 4X100 12mmX1.5 54.1 H

ESCORT LX 92-97 14 X 5 4X100 12mmX1.5 54.1 H
* The offset of a wheel is the distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim / tire assembly. This will cause the tire to stick out away from the vehicle.

H = High Positive or FWD (Front Wheel Drive) typically 45,40,35 offsets
M = Medium Offset or RWD (Rear Wheel Drive) Typically +20 offset
L = Low Offset or RWD (Rear Wheel Drive) Typically 0 offset

 

[thenorm]

its the centre bore.

for example the escort GT wheel centre bore is 54.1mm.

when shopping for wheel make sure the center bore of you new wheel is larger than 54.1mm. or else you'll need to get then machined larger.

luckily i think almost all wheels are larger than that.