EH 15inch wheel offsets

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EH 15inch wheel offsets

by Joe Irvine » Thu Jan 14, 2021 6:40 pm

Hi All, new to the group.Currently putting a 253 into my eh and have an enquiry regarding wheel offsets.The eh has modified hr front end the hq disks and the rear is a shortened borg warner with hq drums.The diff is the same width as the original diff.I have no idea how to work out what the offsets should be if running 15inch rims.I was hoping 6inch front and 8inch back.Does anyone know.Cheers Joe
 
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Re: EH 15inch wheel offsets

by Harv » Fri Jan 15, 2021 7:47 am

G’day Joe,

It’s a complex question, as clearance to things like steering arms, tie rods, caliper/drums, ball joint grease nipples etc make a big difference to how much offset you can run.

There are rules around track increase and tyre width that you will need to meet. As an example, 6/8” wheels on an EH meet NCOP requirements, though are limited to a 205 tyre. Best to check with whoever is certifying the vehicle (probably an engineer given the changes already made). The rules are guidance, and each certifier interprets them differently. As an example, some engineers set track limits based on the EH diff spec, others use the BW diff spec. Either way meets the rules... just interpreted differently.

If it was me:
a) contact engineer, work out what rules/limits they want you to meet.
b) buy a cheap 15” steel wheel from the wreckers and mock it up. Use washers to space the wheel in/out until you have clearance and still meet the rules.
c) measure the offset from your mock-up and buy your new wheels.

Cheers,
Harv
 
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