Sorry I did search - honest!

[half-9 0]

OK - First apologies its an old topic. And I am really killing this one, sorry. I have searched on the forum, but can't find a solution...

 

I have been calculating (on a spreadsheet) different wheel widths and the impact on the width of spacer needed to fit them (I intend to modify the arches).

 

I started with what I think are the original fitments 6.5J x 15, et 33

I have assumed that 6.5j = 6.5 inches - Is this right??

 

Anyway - by my calculations 6.5J/inches converts to overall rim width of 165.1mm which when divided by 2 gives 82.55mm plus the offset +33 (mm?) equates to a rear rim width of 115.55mm. SO the distance from the wheel mounting face to the rear most edge of the original rim is 115.55mm.

 

 

The logic I am applying here is that as long as I maintain approx the same distance between mounting face & rear rim edge, then I can get a alloy wheel as wide as I like but will then need serious arch mods to house it. (I hope your following me coz this is driving me nuts!)

 

I then calculated for a variety of width & et combinations.

 

E.g. I read Blue_Joe has 7.5j x 17 rims et 52 plus 25mm spacers

 

SO 7.5J = 190.5mm, centreline is therefore 95.25mm plus wheel offset of +52 = 147.25mm as the distance from mounting face to rear rim edge. Hence he needed 25mm spacers which then reduced that distance to 122.25mm which is comparable to the original 115.55mm ( so clearance behind the alloy must have deteriorated by only 6.7mm)

 

Great!! - but I think my theory is flawed as original 6.5J wheels were dressed in 195/50/15 tyres - which implies that the rim miust be at least 195mm wide not 165mm as per my theory above.

 

I am confused by this. Can anyone shed anylight on this? Also how do I post my spreadsheet calcs on the forum so that someone can put me out of my misery.

 

ANY help other than recommending a psychiatrist would be much appreciated.

 

Cheers

[Jim Bowen 1]

lots of info here

 

http://www.tirerack.com/tires/tiretech/tirespecskey.jsp