Wheel offsets - again!

[SteveP]

Sorry about this but I have a (another) question for people who have switched from 15" down to 13" rims

 

When doing this, do you find that the inside edge of the rim to the wing stay distance remains constant or increases?

 

The reason I ask is because of these calcs on offsets based on figures people have already suggested(forgive all the definitions, but I've been stung before when buying new wheels) :

 

15" Prisoners have marked on their rim ET13 which I take to be 13mm positive offset i.e. the mounting face is 13mm closer to the outer edge of the rim compared to the centre line

 

6 X 13" rims having a 18mm positive offset would mean that clearance between wing stay and rim increases by 1mm but the outer rim would be 11mm nearer the body work i.e. narrowing the track of the car

 

If all of the offsets were actually negative (e.g Prisoner ET13 actually means 13mm negative offset), then the reverse would be true and the clearance between wing stay and rim would increase by 11mm and the outer rim only be in by 1mm i.e. maintaining the track of the car

 

So which is it? People who have done it, has your track narrowed or stayed the same?

 

Thanks for hanging in there with me on this one

SteveP

[SteveP]

I've probably answered my own question having just been out to measure my existing wheels.

 

Prisoners do have positive offset (despite what Tony Weale's book says ), so assuming 6 x 13 rims have 18mm positive, the inside edge clearance remains the same and the outer edge moves in a bit, giving that sunken look.

 

I think that's cleared it up!

 

SteveP

[SteveP]

I thought that I'd update this with information received directly from KN wheels

 

For the 6 x 13" KN Minator rims as supplied to Caterham direct, the offset is 23mm positive - they do not manufacture an 18mm offset wheel, but they do have a 16mm version.

 

So that's that!

 

SteveP