Who really knows about ET?

[Dutchone]

What I mean by ET is wheel offset.
I have a 96 Griff with the standard 7 spoke Estorils and I am looking to change them to larger and more up to date alloys.

Although going for larger wheels, I still intend to keep the circumference of the tyres the same as standard by using lower profile tyres.

I now want to get the new wheels with the same 'offset' as standard and hence this topic - The rear wheels are 7.5J and are cast with an offset figure (ET) of 35 on the inside face.

Reading wheel manufacturers data I am led to believe that 'offset' is the dimension (wheel in section) from the centre-line of the tyre well to the face that bolts it to the hub.

I have confirmed my rear wheels are 7.5J i.e 7.5 inches wide (190.5 mm) (measured across tyre well) and the dimension from the centre-line of the tyre well to the wheel/hub face minus the the half width is 49 mm i.e the supposed offset.

I cannot see how I can get to a figure of 35 no matter how I measure it!

Question: what am I doing wrong? Anybody got any suggestions?

Cheers, Paul

[number 7]

Dutchone said:

What I mean by ET is wheel offset. I have a 96 Griff with the standard 7 spoke Estorils and I am looking to change them to larger and more up to date alloys. Although going for larger wheels, I still intend to keep the circumference of the tyres the same as standard by using lower profile tyres. I now want to get the new wheels with the same 'offset' as standard and hence this topic - The rear wheels are 7.5J and are cast with an offset figure (ET) of 35 on the inside face. Reading wheel manufacturers data I am led to believe that 'offset' is the dimension (wheel in section) from the centre-line of the tyre well to the face that bolts it to the hub. I have confirmed my rear wheels are 7.5J i.e 7.5 inches wide (190.5 mm) (measured across tyre well) and the dimension from the centre-line of the tyre well to the wheel/hub face minus the the half width is 49 mm i.e the supposed offset. I cannot see how I can get to a figure of 35 no matter how I measure it! Question: what am I doing wrong? Anybody got any suggestions? Cheers, Paul

As I understand it offset is the distance between the centre line of the wheel and the wheel mounting surface. Not sure why you're referring to it as the tyre well, although it should be one and the same thing. Are you measuring with the tyre off. Don't forget that the nominal width is the distance across the tyre mounting faces, and that the total width of the rim might be 25mm or so more than that. If you've got the tyre off, just measure the total width across the rim, divide by 2 and take a measurement from the outer face of the rim to the mounting hub mounting surface. Taking one dimension from the other will give you the offset. Are you mixing up nominal wheel widths with a measurement from the outer face of the rim maybe?

7.