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Wheel Offset?
asn163 - 1/12/05 at 08:48 PM

For 15"x7" wheels with 195/50/15 tyres, what is the correct offset for an Indy?

ET35 or ET38?

Thanks,

Simon

donut - 1/12/05 at 08:49 PM

ET38 springs to mind.

phelpsa - 1/12/05 at 08:56 PM

quote:
Originally posted by donut
ET38 springs to mind.


Bang on although it really makes no visible difference!

ReMan - 1/12/05 at 09:23 PM

quote:
Originally posted by phelpsa
quote:
Originally posted by donut
ET38 springs to mind.


Bang on although it really makes no visible difference!


But the ET35 will stick out by another 3mm right?

Phil. S - 1/12/05 at 09:49 PM

I thought it would be the other way round, i.e. that the 35mm will be narrower

ReMan - 1/12/05 at 10:02 PM

Just checking

RichieC - 1/12/05 at 10:18 PM

The higher the number, the less they will stick out.

ET38 will be 3mm less than ET35

ditchlewis - 2/12/05 at 08:34 AM

I used Et38 and they are only just inside the rear wings.

Ditch

Phil. S - 2/12/05 at 10:25 AM

quote:
Originally posted by RichieC
The higher the number, the less they will stick out.

ET38 will be 3mm less than ET35


Are you sure about that? If the ofset is greater that means the back plate is further in from the centre line of the wheel, so the track will be wider. Negative ofset has the reverse effect. So the greater the negative ofset the further in the wheel will sit.
I switched from +5 to +24mm ofset and the latter were much wider.

greggors84 - 2/12/05 at 11:13 AM

I always took a positive offset to be one where the mounting surface was further out than the centre line, like on most wheels.

The ET18 caterham wheels i tried stuck out the arches loads, the ET38 ones are much much better.

I think in the range of 35 to 38 should be fine for an Indy, any less and you will start messing with the geometry noticably.

[Edited on 2/12/05 by greggors84]

Peteff - 2/12/05 at 11:14 AM

Did you swap from a 5J wheel to a 7J at the same time?. It sounds like you are confusing width with offset.

tadltd - 2/12/05 at 12:05 PM

All the info you need on wheel offsets, PCD's, etc...

http://www.turner-auto-design.com/wheeltech.htm

progers - 2/12/05 at 01:58 PM

ET 38 is the ideal offset for a 6" wheel in an Indy. For a 7" wheel you will need to increase the offset if you want the wheel outside edge to be in the same position. In this case it will need to move 12mm (1/2" as the wheel is 1/2" wider relative to the centre of the wheel. Thus you will need an offset of et50. In practice et45 will still fit inside the wheel arches OK, with et38 you will be almost flush with the wheel arches which could be an SVA fail.

Cheers

Paul

asn163 - 2/12/05 at 08:14 PM

Thanks guys for the info.

I have decided to play safe and have gone with 15" x 6.5" ET38 Wolfrace Street Octanes.

Simon

[Edited on 2/12/05 by asn163]

[Edited on 2/12/05 by asn163]