Different offset - will it cause a problem?

[havoc]

Struggling with this one - offset on current wheels (225/40/18) is 45. Offset on a smaller set I'm looking at for winter tyres (205/55/16 to preserve rolling radius to ~1%) is 37.

What effect is this going to have on the car, uncorrected?
Will it cause any problems?
Is it possible to fit spacers to solve this, or is the difference 'the wrong way'?


Edit: Found a website that suggests OE offsets for the car are 40-45.

Edited by havoc on Sunday 31st October 21:28

[redstu]

To me this means your wheels (and tyres) will be 8mm closer to suspension , wheelarch etc than your current set up ,or 3 mm closer than the minimum normal range. So it might be a problem.

[davepoth]

As has been said, the mid point of the wheel moves 8mm closer to the arch, which would be a problem except that the new wheels are 20mm narrower (205 section vs. 225 section) so it all more or less balances out IMO.

[havoc]

redstu said:

To me this means your wheels (and tyres) will be 8mm closer to suspension , wheelarch etc than your current set up ,or 3 mm closer than the minimum normal range. So it might be a problem.

This is what I've been thinking. But the new ones would be 7J running 205 tyres, not 8J running 225 tyres - so the inside rim will actually be 2mm further out than current. So clearance to the suspension and to the wheelarch isn't an issue.

I'm more interested in the movement of the centre-patch (increasing track by 16mm from current / 6mm more than (is that right?) the minimum standard track), and the effect that will have on the operation of the suspension / steering?
- It's a big change from current
- But it's only a 3mm per side change from OE specs


Edit: Just seen Dave's note above

Edited by havoc on Sunday 31st October 21:54

[davepoth]

havoc said:

redstu said:

To me this means your wheels (and tyres) will be 8mm closer to suspension , wheelarch etc than your current set up ,or 3 mm closer than the minimum normal range. So it might be a problem.

This is what I've been thinking. But the new ones would be 7J running 205 tyres, not 8J running 225 tyres - so the inside rim will actually be 2mm further out than current. So clearance to the suspension and to the wheelarch isn't an issue.

I'm more interested in the movement of the centre-patch (increasing track by 16mm from current / 6mm more than (is that right?) the minimum standard track), and the effect that will have on the operation of the suspension / steering?
- It's a big change from current
- But it's only a 3mm per side change from OE specs


Edit: Just seen Dave's note above

Edited by havoc on Sunday 31st October 21:54

The two main problems are fouling and excess wear on the wheel bearings by having too much offset away from the wheel bearing. Since none of the new wheel will be outside of where the old wheel was, it shouldn't cause a problem. Looking at some google diagrams, this one in particular:

[img]http://www.partsprovider.net/images/wheel-offset-backspace.gif[img] the reduction of the offset will leave the outside edge of the wheel about 2mm in from where it was, and the inside edge 12mm further out.

[v8will]

You are decreasing the offset so in theory that should move the wheel further away from the suspension and brake components. However as you are decreasing the wheel width by 1" and the tyre width by 20mm this will negate the change in offset.

If my sums are correct you are decreasing the back space (rear of wheel to hub mounting face) from 160mm to 139mm. So the change in offset will make faff all difference. The difference in scrub radius would be very similar too so no worries there.

Your only concern will be that the new wheels fit over your front brakes. I can't see any other negative results. On the plus side the deeper tyre sidewall will increase ride comfort and you may actually see a reduction in unsprung weight.

[havoc]

Thanks Will. Brake clearance shouldn't be an issue but I'll double-check.

I think it's all irrelevant now though - just discovered current wheels are ET51 - it's the replica Monza-IIs that are ET45* - I was confused by a website that said the range of offsets for the Golf are 40-45, so I'm guessing the GTi must have different suspension or different hubs.

Sooo...if the GTi does have a different hub position to a stock GTi, then all bets are off here, and I need to look for ~ET45-55.

Bother...


* So most of the vendors on eBay selling "Monza IIs" are selling replicas!

[v8will]

havoc said:

Thanks Will. Brake clearance shouldn't be an issue but I'll double-check.

I think it's all irrelevant now though - just discovered current wheels are ET51 - it's the replica Monza-IIs that are ET45* - I was confused by a website that said the range of offsets for the Golf are 40-45, so I'm guessing the GTi must have different suspension or different hubs.

Sooo...if the GTi does have a different hub position to a stock GTi, then all bets are off here, and I need to look for ~ET45-55.

Bother...


* So most of the vendors on eBay selling "Monza IIs" are selling replicas!

Golf V? ET42 or higher only, ET37 is less than ideal for this car

Any Golf V or VI regardless if it's a cooking model 1.4 or a R32 needs ET42 or higher, definately ET45 if lowered. OE offsets are around ET51 as you suggest

[Matt_N]

Going from an 8J ET51 to a 7J ET37 will give you 27mm more inner arch clearance and will push the wheel lip out 1mm.