Ultimate guide for Airlift Front wheel fitment vs Double Bellow Bag/CUP system

[thien]

Originally Posted by frs_94

i am running 18x9.5+34 in the front and it looks to me like i am rubbing. you guys think i could fix this by adding a spacer and some camber.

Yeap! That's how you fix it. I did the same. Remember though, fronts can't camber with plates. The bag rubs the body/frame

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[lukey86]

Originally Posted by frs_94

i am running 18x9.5+34 in the front and it looks to me like i am rubbing. you guys think i could fix this by adding a spacer and some camber.

Running as much positive camber as you can get from camber bolts and off-setting this by adding more negative camber at the plates may work depending on your tire profile

[LXXXV1]

Originally Posted by lukey86

Merry Christmas all!

I figured I'd throw this up here because everyone seems to be asking wether specific wheels will fit or not when it really isn't that hard to figure this out on your own with a little basic math, wheel knowledge and of course a specific reference which in this case is a measurement from the hub face to the air bellows (all of the measurements I'm using are with the bags at 30psi as this represents the bellows at their narrowest point. Also remember that due to the shape of the bellows different diameter wheels, 18" 19" etc. may have different clearances so all measurements will be based on the more common 18" wheel)

so to get started first off you need know how to know how to reverse engineer the measurements from a specific wheel/offset combination. To do so is easier than you might think. To start off, you will need the true width of the wheel in question, which is not actually the width as you know it. Advertised widths and true widths are not the same. The advertised width is measured from inside lip to inside lip and the true with is of course from outside to outside. Most of the time, actually about 99.9 percent of the time with most common wheels this outside measurement is approximately 1 inch wider than advertised width. So using my wheels as an example, on the box it says they're 9.75 inches wide. But based on our knowledge of true width we know that they're actually 10.75 inches wide. Or if you have an 8 inch wheel then you know that the true width is 9 inches etc.

So with that out of the way we now need to figure out our offset measurements but in order to do so we need to convert our inches to mm as it is in mm that all offset measurements are made. So our example is 10.75 inches. I just have to Google 10.75 inches to mm and I get a result straight away: 273.05mm, we can drop the .05 as its too small a number to make much of a difference. next, we divide my 2. This gives us 135.5mm.

So now a little on offset. It's rediculously simple. Offset is simply the exact location of the hub-face portion of the wheel relative to the centre of the rim. So the measurements you see are how many millimeters the hub-face is from the exact centre of the wheel. The - and + signs simply tell us wether that measurement is towards the inside or outside of the wheel. So +20, for example means that the hub-face is 20mm from the center of the wheel and the fact that it's positive means that this measurement is taken from the center OUT rather than in.



So now that we know what offset is, all we have to do is apply the theory to our example wheel and we can successfully reverse engineer it's measurements. We've already measured and converted our wheel and halved the conversion, so all thats left to do is apply the offset to work out our measurement from the hub-face to the furthest inside point on the wheel. Because our wheel is +20 we simply add 20mm to our measuement. So 135.5 + 20 + 155.5. Success! We now know that the actual distance from the hub to the furthest extremities of the rim is 155.5mm. I also know that from the outside of this particular wheel to the air bellows (at 30psi) is 15mm. So not only have we reverse engineered the measurements of my wheels but we have also found our all important reference! Based on these measurements we now know that on any car the distance from the face of the hub back to the air bellows (for an 18" wheel and once again at 30psi) is 170.5mm (155.5mm + 15mm)

So based on that figure (170.5mm) you can now apply those basic principals to any wheel size/offset combo and determine whether they would fit!

So another example for clarification:

Lets use th above mentioned 18X9.5 +45...

First, add an inch:

9.5" + 1 " = 10.5"

Next, convert to mm:

10.5 inches to mm = 266.7 (round off to 267)

Now divide by 2:

267 / 2 = 133.5

Now add the offset (if the offset were negative we would subtract)

133.5 + 45 = 178.5

Lastly compare to our reference:

Our measurement of 178.5 is larger than our reference of 170.5. So it seems that unfortunately this wheel is too large by approximately 8mm (sorry lol)

(just remember that all of these measurements are focused purely on the wheel without tires. Meaty tires can affect your measurements so make sure to include any tyre overhang ect to your measurements)

And thats it! apply the same theory as above to any wheel to get an approximate idea of whether they will fit or not. Happy Holidays!

thank you!

Based on your math, if I run 18x8.5 +45, I'd get 165.65 in the front. If you're fitting 170.5, then 18x8.5 +45 should fit right?? Lol I can't find where the point of reference is to the bag except you're 30psi being the narrowest reference.

[lukey86]

Originally Posted by LXXXV1

thank you!

Based on your math, if I run 18x8.5 +45, I'd get 165.65 in the front. If you're fitting 170.5, then 18x8.5 +45 should fit right?? Lol I can't find where the point of reference is to the bag except you're 30psi being the narrowest reference.

Yeah should fit the reference I calculated from my own wheels, by working out the distance from the hub-face of the wheel back to the inside lip of the rim and then measuring the distance from the rim to the bag, adding these two together gives you the distance from the hub of the car back to the bag (170.5mm) which is the same for everyone, so long as theyre running 18s

[_frs]

I know this is an old thread but I need advice and can offer insight. I'm running 18x9.5 +20 on a 235/40 tire and I was rubbing my bags. I added 5mm spacers which still work on stock studs and it fixed the problem. The only problem is now I rub my fenders too much even with the roll. I am thinking of adding bigger spacers plus camber bolts so that the bag won't rub the wheel if I camber in (without bigger spacers) and I hope that will solve the problem especially on stock studs. Does anyone have any insight as to how big a spacer you can safely run on our studs? I have 5mm and am doing fine but just need bigger to clear the bag when I camber in.

[all4spl]

were you rubbing on tire or the rim? im battling what size tires and spacer to run on a 18x9 +33 wheel with air bags.

[lukey86]

You could also manually raise the struts a little, not quite as much overall drop but it helps heaps with clearance


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[dito]

Originally Posted by _frs

I know this is an old thread but I need advice and can offer insight. I'm running 18x9.5 +20 on a 235/40 tire and I was rubbing my bags. I added 5mm spacers which still work on stock studs and it fixed the problem. The only problem is now I rub my fenders too much even with the roll. I am thinking of adding bigger spacers plus camber bolts so that the bag won't rub the wheel if I camber in (without bigger spacers) and I hope that will solve the problem especially on stock studs. Does anyone have any insight as to how big a spacer you can safely run on our studs? I have 5mm and am doing fine but just need bigger to clear the bag when I camber in.

Youre wheel size is perfect specs. Same specs as mine. But your tires are pretty fat. Im running 215/35. A good stretch but no rubs at all and airs out all the way

[SleepingPanda]

When you guys say the bag rubs the frame. Are you talking about the shock tower? Has anyone tried gaining clearance with a hammer to the strut tower?

[lukey86]

Originally Posted by SleepingPanda

When you guys say the bag rubs the frame. Are you talking about the shock tower? Has anyone tried gaining clearance with a hammer to the strut tower?

Yeah I've done just that on two cars now, also a couple of bolts and plastic clips to be removed as well, no rubbing at driving height and only a little when fully up but it doesn't hurt


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[dito]

Yeah be sure to remove that plastic clip behind the bags. It ripped a chunk of layer of my bags lol

[lukey86]

Originally Posted by dito

Yeah be sure to remove that plastic clip behind the bags. It ripped a chunk of layer of my bags lol

Yeah I learned by ripping a hole in one of mine lol it was on one of the bolts


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[SleepingPanda]

Originally Posted by lukey86

Yeah I've done just that on two cars now, also a couple of bolts and plastic clips to be removed as well, no rubbing at driving height and only a little when fully up but it doesn't hurt


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So once you clearanced it with a hammer. Are you able to use all of the Camber setting on the plate?

[lukey86]

Originally Posted by SleepingPanda

So once you clearanced it with a hammer. Are you able to use all of the Camber setting on the plate?

Yeah, I have mine maxed out