steve m
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| posted on 29/10/10 at 01:40 PM |
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calculating wheel et ?
I am confused, (been on nights al week )
i would like to change my wheels on the locost <, for lighter and more stylish ones, also to lose the wheels spacers on the back
so if my wheels are 7x13 (they are at present) and i want the mounting flange of the wheel to be 50mm in from the back face of the wheel,
My rear wheels would be quite a big negative offset
what would be the "et"
hope this makes sense, as its doing my head in !!
[Edited on 29/10/10 by steve m]
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loggyboy
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| posted on 29/10/10 at 02:16 PM |
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7inch = 178mm
178/2 = 89 centre line
ET is measured from the centreline
89-50 = 39 and that would be negative
Most wheels have a positive ET, ie ford is about 38, vauxhall is 49.
Meaning you would need 77mm spacer to acheive a 39mm negative ET on standard ford wheel with 38mm (pos) offset.
[Edited on 29/10/10 by loggyboy]
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CRAIGR
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| posted on 29/10/10 at 03:00 PM |
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http://www.1010tires.com/WheelOffsetCalculator.asp
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v8kid
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| posted on 29/10/10 at 05:09 PM |
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Yup but the backspace is measured from the outside of the inner rim and the width is measured from the inside edges of the rim.
In effect this makes the ET about 12mm more. i.e. -52
This www.rimsntires.com/rt_specs.jsp explains it better
[Edited on 29-10-10 by v8kid]
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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snapper
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| posted on 29/10/10 at 06:29 PM |
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The car wheel bible shows this well.
I have deliberated long and hard on this and look at it this way,
1. if the wheel has an ET of 0 then the centre line of the rim is level with the mounting face.
2. Making the back space longer, pushed the mounting face closer to the outside of the wheel, the difference is +ET, -ET if the back space is less.
3. It becomes more difficult to picture when you increase wheel width and want to keep back space the same.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Peteff
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| posted on 29/10/10 at 07:13 PM |
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quote:
Originally posted by snapper1. if the wheel has an ET of 0 then the centre line of the rim is level with the mounting face.
Carbible picture shows it. Why do they mix their inches and millimetres as it confuses me
[Edited on 29/10/10 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Mark Allanson
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| posted on 29/10/10 at 08:35 PM |
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What is generally overlooked is that if you fit a 195 70 13 tyre to a 6x13 wheel with an 19mm offset, it will be in exactly the same position as
fitting it to a 8x13 wheel with the same 19mm offset.
It is always the tyre that will foul any bodywork than the wheel. You will have to check the scrub radius though.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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steve m
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| posted on 29/10/10 at 09:30 PM |
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I do have PLENTY of room under tghe rear arches
i also came up with -52 so that a good start
now to look for some 2 wheels 7x13 -52
and 2 7x13 et38
steve
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v8kid
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| posted on 29/10/10 at 09:46 PM |
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You don't have to get -52> suppose you can only get -32 if you add a 20mm spacer that makes it -52.
More commonly with a -18 offset you would require a 34mm spacer which is probably as far as you woud want to go.
If you don't like the idea of spacers you could buy 3 piece wheels which you can build to any size you want.
For a 7" rim you would want around a 3" inner rim and a 3.5" outer rim. (the center is approx 0.5" . This will vary depending
on the offset built into the differnt centers
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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