Wheel changes ?

tyre size - ideal is 215 45 17 or 225 45 17.

You need wheels with a pcd (stud pattern) of 4 x 108.

Most 8 stud multifit wheels have 4x100 and 4 x 108 patterns, but you need to check
 
tyre size - ideal is 215 45 17 or 225 45 17.

The better size is 215/45R17 for speedo accuracy.

Also the centre bore must be 63.4. Aftermarket wheels usually achieve this with spigot rings or if you go for a genuine Ford wheel (e.g. from another 4 stud Ford ST200, ST170 etc) spigot rings are not necessary.

Offset ranges from ET35 to ET46.
 
Rochford Tyres (www.alloywheels.com) have a nice selection of wheels available for the Cougar. They supply the spigot ring and the new nut set included in the price. Some styles are pretty cheap. I got mine from there. It was cheaper than buying locally even if you include the shipping to the other side of the world.

ET35 offset (for 17x7) looks the best in my opinion. I wouldn't want the wheels sitting any further under the gaurds now I can see how they look once fitted.

I put 225/45ZR17's on my wheels. Speedo is 0.5km/h out (when it reads 100 I'm really doing 100.5). I had it checked on Friday. With the standard size 16" wheels/tyres the speedo was out the other way (showing 100 but only really doing 97).
 
Rochford Tyres (www.alloywheels.com) have a nice selection of wheels available for the Cougar. They supply the spigot ring and the new nut set included in the price. Some styles are pretty cheap. I got mine from there. It was cheaper than buying locally even if you include the shipping to the other side of the world.

ET35 offset (for 17x7) looks the best in my opinion. I wouldn't want the wheels sitting any further under the gaurds now I can see how they look once fitted.

I put 225/45ZR17's on my wheels. Speedo is 0.5km/h out (when it reads 100 I'm really doing 100.5). I had it checked on Friday. With the standard size 16" wheels/tyres the speedo was out the other way (showing 100 but only really doing 97).

On the track or private road obviously