27 replies to this topic

[76lxhatch]

Mine is flared, but I had to get the 15x10 rears modified from 4.25" to 5.25" backspace to fit comfortably without rubbing the flares.

You could quite happily run 225s or maybe 235s on a 7" wheel.

[mitchg]

I run 235s on my 14 x 7s. But I believe you can run 245s.

[76lxhatch]

But the overall diameter is 668

mm? That is very big, might be a problem

[76lxhatch]

Actually I'm sure I recall Rory mentioning something about machining the discs to do that

[dattoman]

I wouldn't mod the discs

Its cast iron and not exactly the best quality
And you'd have to do it every time you need to change them
Do the wheels and you only have to do it once...and they will be a better grade of alloy thats better machined

Of course... get a pro to look at this first

[ls2lxhatch]

I think you will need more than 5 mm removed to avoid tyre rub.

I have Toyo T1R 235/40/17 fitted on an 8" rim, the tyre overhangs the rim by 2-3 mm. There is a 35 mm gap between the tyre and the outside of the wheel arch. When the car is on the bump stops the tyre is within a few mm of the inner guard. It would appear the lip is about 20 mm wide which means you would need to be around 15 mm inside the lip to avoid tyre rub.

Based on your measurements you would need to remove 5 mm (108-105+2) to stop the tyre touching the lip and 20 mm to stop the tyre from touching the inner guard. If you need to have the car engineered with the rims then you may get knocked back for insufficient tyre clearance. You should also keep in mind the the diff will move at least 5 mm for side to side during moderate cornering. You should check that the diff is not sitting off centre when you take your measurements.

The 17x7 4.5 backspace with a 225/45/17 (OD 633 mm) may be the easiest solution.

There may be enough spline on the factory axles for you to be able to trim 20 mm of the end of each axle and shorten the housing.

Edited by ls2lxhatch, 07 July 2009 - 08:57 PM.

[76lxhatch]

There may be enough spline on the factory axles for you to be able to trim 20 mm of the end of each axle and shorten the housing.

10mm maybe, definitely not 20mm

[ls2lxhatch]

It would also be worth checking what the track will be with the 4.25" and 4.5" backspace. I am not sure what the NSW rules are however in WA you can not reduce track and can only increase track by a maximum of 25 mm. The standard track puts the rim close to the centre of the wheel tub.

Specifications - Rims, Tyres And Track

I would also check the clearance between the shock and the tyre with both rims. There should be plenty of room but it is still worth checking.

[ls2lxhatch]

The first point of contact on the inside of my rear wheel is the shock, I had to switch to smaller diameter shocks to get sufficient tyre clearance.

[76lxhatch]

There's no way an 8" wheel with 4.75" backspace will get that close on the inside

[ls2lxhatch]

Whether the shock or the chassis rail hits first depends on the diameter of the tyre. Tyres with a large rolling diameter will hit the chassis rail before they hit the shock. Tyres with a small rolling diameter will hit the shock first.

The shock in the car above has been moved inboard about 40 mm at the base as part of the BW diff conversion. This will result in a small improvement in the clearance at the top a the shock.