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Mixed offsets
Mix - 27/9/05 at 12:03 PM

I'm at the stage where I want to buy my wheels but am a bit unsure of the best approach.
On the front I have Cortina uprights which I think are designed for an ET15 offset.
At the rear I am using Sierra parts and dimensions for the IRS which originally used ET 38.
Gut reaction says to try and buy the corresponding offset wheels. Is this the right approach?
Does anyone have any experience of wholesalers supplying two pairs of wheels with different offsets?
Is the offset only critical on the front wheels?

Cheers Mick

[Edited on 27/9/05 by Mix]

andyd - 27/9/05 at 12:12 PM

quote:
Originally posted by Mix
Does anyone have any experience of wholesalers supplying two pairs of wheels with different offsets?

No experience with regard to offset but Compomotive will do you two wheels in different widths to the other two. They also do full custom jobs so I'd guess if you wanted differing offsets they'd do that too.

indykid - 27/9/05 at 12:14 PM

afaik, offset is most important on the front to maintain scrub radius, and for the back, as the wheels don't steer, it's less important. as long as you don't go too far, so altering stress on the bearings, you should be alright.

if you run et15 all round, the fronts will be right, and the rears will be spaced by 23mm. as long as there's room in the arches, it should be doable.

just waiting to be shot down
tom

tobymack - 27/9/05 at 12:37 PM

Are you sure you want to maintain that scrub radius? I got the impression that the cortina upright gives a little too much as it is.

Anyway, for what it is worth, I have just changed from ET19 to ET36 at the front and it has given nicer (IMHO!) handling! This is on a westfield but it is cortina uprights and I think very similar geometry to the locost. (5 deg castor, 1 deg camber, zero toe)

At the back it is not so good, I can feel the inside wheel lifting a bit more so I am fitting wheel spacers to get it back to more like it was before.

handling feel is a very personal thing so, if at all possible, I would try before you buy.

Toby

pbura - 27/9/05 at 12:59 PM

If you can get ET38 wheels for the front, then that would be the way to go, IMO. Never understood the Cortina scrub radius (about 3-1/4" IIRC).

Mix - 27/9/05 at 05:30 PM

Toby / Pete

That's what I would like to do, (fit ET 38s all round), but I'm a bit concerned if it ever gets to SVA time about the self centering. I know I should read up on this aspect of suspension geometry but 'so many things to do so little time' so can anyone say if this is going to improve or detract from the cars ability to self center.

Thanks Mick

Peteff - 27/9/05 at 06:30 PM

I use standard Sierra steel rims on my Cortina fronts and you can actually feel it trying to centre, unlike some of the other cars I've been in.

Mark18 - 27/9/05 at 07:05 PM

I have the same setup, if you use 20mm spacers on the front that gives you the right offset - ET18 + 20 = ET38. I was aware of the cortina scrub radius issue but I'm running cortina and sierra track widths and could stand to gain the extra width up front.

Mark