How wide tyres and wheels for an EH?

Driveline (including transmissions, differentials, tailshafts) discussion.

Re: How wide tyres and wheels for an EH?

by Tuf064 » Wed Jun 01, 2011 11:37 pm

Back to the offset, I thought you had it right the first time around Pete. I thought if you had + offset the rim would be pushed out more, or, in other words, adding + offset would increase the track width.

Well, looking at this chart anyway: http://www.dragway.com.au/images/wheel-chart.pdf
 
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Re: How wide tyres and wheels for an EH?

by Tuf064 » Wed Jun 01, 2011 11:47 pm

Comparing that chart to one i drew of my own to try and understand it - is the following correct?



Black indicates rim width along with the centre line being where it bolts against the hub.



Red indicates the side the hub and axle is on.



1= a rim with 0 offset.



2= increasing the distance between the hub and edge of the rim (+ offset of say 5)



3= increasing the distance between where the rim bolts to the hub and the lip on the inside of the rim (- offset of lets say 5)



Therefore I would have expected that if you want a "deep dish" on your rim for show you would want to go for + offset.



And if you want a flat faced rim (such as a late model commodore) you would have - offset.



Sorry about the playschool looking pictures, its the best I could do in paint





 
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Re: How wide tyres and wheels for an EH?

by peter_ejeh » Thu Jun 02, 2011 12:27 am

Nah. Deep dish wheels typically have negative offset. For Example in Metric modern terms some Commodore flat faced wheel is ET38 for example which is a +38
 
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Re: How wide tyres and wheels for an EH?

by Tuf064 » Thu Jun 02, 2011 12:35 am

Ah ok, so how do you make sense of that dragway form?
 
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Re: How wide tyres and wheels for an EH?

by peter_ejeh » Thu Jun 02, 2011 8:20 pm

Well, looking at their form I would read it this way. If the mounting face of the wheel lives anywhere in the rectangle box called 'Positive offset', then that is what it is called. Because the box called 'Positive offset' is on the front of the wheel area, then if you have a flat faced wheel, then the mounting face will be living in 'Positive' territory.
 
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Re: How wide tyres and wheels for an EH?

by Tuf064 » Thu Jun 02, 2011 8:25 pm

That's what I thought, but cleary the mounting face in on the negative offset side.
 
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Re: How wide tyres and wheels for an EH?

by Ray » Thu Jun 02, 2011 8:29 pm

quote:
Originally posted by holden_stroker

Ah ok, so how do you make sense of that dragway form?



you have your positive and negative around the wrong way in your pic,

think of it this way, you have 2 parts of a wheel...

the rim
the centre

a positive offset pushes the RIM inwards (towards the car), the rim... not to be confused with centre.

pushing the rim inwards is different to pushing the centre inwards, it will achieve a different result
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Re: How wide tyres and wheels for an EH?

by Tuf064 » Thu Jun 02, 2011 8:51 pm

I followed the diagrams on the dragway link I posted above. My rim face diagrams are on the same side they have and so are my positive and negative measurements on the same side as theirs.

I understand how the measurements work now, but it didn't explain why they are the opposite on the dragway form.
 
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Re: How wide tyres and wheels for an EH?

by peter_ejeh » Thu Jun 02, 2011 9:26 pm

The Dragway form is not opposite. If the measurement from centre line to wheelface has to be made in the 'Positive' box area, then that is a 'Positive' measurement.
 
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Re: How wide tyres and wheels for an EH?

by Tuf064 » Sat Jun 11, 2011 11:40 pm

Ahhhhh I finally get it now haha... Boy am I stupid!!
 
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