From Tim Engel:
Europa Wheels
Lotus .......... Lotus ......... Spitfire
Alloy ........... Steel .......... Steel
5.5" ............. 4.5" ............ 4.5" .......... Width
+0.637" .... +1.094" ..... +0.812" ...... Offset, inches
+16.0mm... +27.8mm... +20.6mm ... Offset (mm)
Revolution.. Cosmic ...... Panasport
Alloy ........... Alloy ........... Alloy
6.0" ............. 5.5" ............ 6.0" .......... Width
+1.158" .... +0.938" ..... +0.630" ...... Offset, inches
+29.4mm... +23.8mm... +16.0mm ... Offset (mm)
I measured my Europa wheels, and borrowed a friend's Spitfire wheel. I can't say that every Revolution/ Cosmic/ Panasport wheel 'for' the Europa will have these dimensions, but mine do/did.
And again:
13 x 4.5", +1.062" Offset, +27.0mm ET - Europa Steel Wheels
13 x 5.5", +0.637" Offset, +1.62mm ET - Europa Alloy Wheels
13 x 4.5", +0.812" Offset, +20.6mm ET - Spitfire Steel Wheels
The Twin Cam's Brand Lotus alloy wheels are not only 1" wider than the standard steel wheels, the smaller positive offset moves the wheels outward by 1.062 - 0.637 = 0.425".
Straying a little off-topic, but the Triumph Spitfire steel wheels some Lotus owners use also have less positive offset, which moves the wheels 0.25" outward compared to the Lotus steel wheels.
Regards,
Tim Engel