Advice appreciated on wheel offset and size
Discussion
Folks,
Any advice on the following would be appreciated:
I own a 2010 Octavia VRS hatchback which I have recently fitted (or had fitted for me) a set of Weitec coilovers. These have lowered the car by approximately 30mm.
I would like to do a wheel change, from the standard 18" (7.5" rims, ET51 with 225x40 tyres) wheels to a set of 19's and I worried about rubbing/catching on the arches and/or suspension components.
The new wheels (VMR V710's) come in the correct centre bore & PCD sizes, but the lowest width option is 8.5" and the offset is ET45.
Oh, and to throw another mix into the equation, my car currently has 15mm spacers on the back axle (to bring the wheels out flush with the wheel arch, to match the front).
The guy from the UK distributor (which is too far away to drive to for a try-before-I-buy fitting) has offered me some advice on offset, as has a helpful chap on another forum, but it has now got to the stage where I am more confused than before I started looking into this.
From a purely unscientific 'quick look' I don't have ANY spare room at the moment between the outer edge of the back tyre and the outer wheel arch. I hope to dispense with the wheel spacers when I fit the 19" wheels though.
Any advice?
Any advice on the following would be appreciated:
I own a 2010 Octavia VRS hatchback which I have recently fitted (or had fitted for me) a set of Weitec coilovers. These have lowered the car by approximately 30mm.
I would like to do a wheel change, from the standard 18" (7.5" rims, ET51 with 225x40 tyres) wheels to a set of 19's and I worried about rubbing/catching on the arches and/or suspension components.
The new wheels (VMR V710's) come in the correct centre bore & PCD sizes, but the lowest width option is 8.5" and the offset is ET45.
Oh, and to throw another mix into the equation, my car currently has 15mm spacers on the back axle (to bring the wheels out flush with the wheel arch, to match the front).
The guy from the UK distributor (which is too far away to drive to for a try-before-I-buy fitting) has offered me some advice on offset, as has a helpful chap on another forum, but it has now got to the stage where I am more confused than before I started looking into this.
From a purely unscientific 'quick look' I don't have ANY spare room at the moment between the outer edge of the back tyre and the outer wheel arch. I hope to dispense with the wheel spacers when I fit the 19" wheels though.
Any advice?
Two options:
1: get out there, whip the wheel off and get measuring!
2: Buy the wheels and try them!
It's a minefield, I'll grant you.
I would go for the measuring option. Basically you know you have fixed points in the arch, like your hub face, distance to spring perch, distance to arch liner etc. You also have reference points like you know how your current wheel fits in the arch and the clearances that has. To be honest I found it easier to knock up a 2D CAD model and fix all the known points, so you can then experiment with things like offset and tyre width. Don't forget to take into account the fact that a wheel is physically about an inch wider than its stated width! (An 18x8J for example means the tyre seat is 8 inches wide, but including the lip etc the actual wheel as measured exterior width would be about 9).
Basically there comes a point where you just have to take the plunge, really. Hopefully your research up to that point will see you right!
Good luck...
1: get out there, whip the wheel off and get measuring!
2: Buy the wheels and try them!
It's a minefield, I'll grant you.
I would go for the measuring option. Basically you know you have fixed points in the arch, like your hub face, distance to spring perch, distance to arch liner etc. You also have reference points like you know how your current wheel fits in the arch and the clearances that has. To be honest I found it easier to knock up a 2D CAD model and fix all the known points, so you can then experiment with things like offset and tyre width. Don't forget to take into account the fact that a wheel is physically about an inch wider than its stated width! (An 18x8J for example means the tyre seat is 8 inches wide, but including the lip etc the actual wheel as measured exterior width would be about 9).
Basically there comes a point where you just have to take the plunge, really. Hopefully your research up to that point will see you right!
Good luck...
OwenK said:
Two options:
1: get out there, whip the wheel off and get measuring!
2: Buy the wheels and try them!
It's a minefield, I'll grant you.
I would go for the measuring option. Basically you know you have fixed points in the arch, like your hub face, distance to spring perch, distance to arch liner etc. You also have reference points like you know how your current wheel fits in the arch and the clearances that has. To be honest I found it easier to knock up a 2D CAD model and fix all the known points, so you can then experiment with things like offset and tyre width. Don't forget to take into account the fact that a wheel is physically about an inch wider than its stated width! (An 18x8J for example means the tyre seat is 8 inches wide, but including the lip etc the actual wheel as measured exterior width would be about 9).
Basically there comes a point where you just have to take the plunge, really. Hopefully your research up to that point will see you right!
Good luck...
The UK distributor is saying they've fitted these wheels, in this size, to a lowered VRS in the past with no issues, but have said if I buy them for my car and they don't fit (i.e. they rub/catch) then I can't return them. Bit of an expensive 'plunge' if they don't fit - they are quoting me £1,640 inc. tyres and delivery!1: get out there, whip the wheel off and get measuring!
2: Buy the wheels and try them!
It's a minefield, I'll grant you.
I would go for the measuring option. Basically you know you have fixed points in the arch, like your hub face, distance to spring perch, distance to arch liner etc. You also have reference points like you know how your current wheel fits in the arch and the clearances that has. To be honest I found it easier to knock up a 2D CAD model and fix all the known points, so you can then experiment with things like offset and tyre width. Don't forget to take into account the fact that a wheel is physically about an inch wider than its stated width! (An 18x8J for example means the tyre seat is 8 inches wide, but including the lip etc the actual wheel as measured exterior width would be about 9).
Basically there comes a point where you just have to take the plunge, really. Hopefully your research up to that point will see you right!
Good luck...
Here is what someone on another forum advised:
7.5" ET51 with spacers 15mm make 7.5" ET51-15= ET36. Difference between 7.5 and 8.5 is 25.4mm in both directions.Means 12.7mm more out.
But the ET is 45 instead of 36 means 9mm more in.
12.7 more out minus 9mm of the ET are 3.7mm more out
than std Zenith with the 15mm spacer.
The VMRs are exactely 1" wider, 25.4mm.
Means the will be 25.4mm-3.7mm=21.7mm more on the inside.
I don't really want to have to raise the car back up again in order for these wheels to fit, especially after spending close on £900 to get the Weitec coilovers fitted.
Try it and see is always the way I've done it. A 30mm drop isn't that much. Where I have made mistakes in the past is getting the right profile of tyre to suit. Putting larger diammeter wheels on means your pushed to lower profiles but sometimes a larger profile will look better and fill the arches.
Some of the more friendly wheel shops may help you out and try different tyres on to see if they fit. Aceleration/speedo won't be as per the book if your changing the diammeter.
Some of the more friendly wheel shops may help you out and try different tyres on to see if they fit. Aceleration/speedo won't be as per the book if your changing the diammeter.
You'll need to check that the diameter of the new wheels plus tyres is the same as the diameter of the old wheels plus tyres to make sure you don't throw your speedo too far out of whack (unless there's an easy way of re-calibrating). There are a few tyre size calculators on the web that might help. I've used this one in the past:
http://www.miata.net/garage/tirecalc.html
As for width and off-set, the off-set of your existing wheels should be stamped on the rim somewhere. I found it easiest to draw myself a little diagram (similar to the one on this website: http://www.tirerack.com/wheels/tech/techpage.jsp?t... ) and work out the sums on paper.
Hope this helps...
http://www.miata.net/garage/tirecalc.html
As for width and off-set, the off-set of your existing wheels should be stamped on the rim somewhere. I found it easiest to draw myself a little diagram (similar to the one on this website: http://www.tirerack.com/wheels/tech/techpage.jsp?t... ) and work out the sums on paper.
Hope this helps...
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