The most I've ever had to put in them was 15lbs, and that was loaded and towing my camper. If I put the max in ( 35lbs) it actually lifted it another inch and made it pretty stiff! You really can use the stock size bags, I did for years with OME coils and a 2" coil spacer 'ta boot. When I switched to my FOA Coils, they were 4 " longer than stock so that's why I went to the longer bags, that and it looks much cleaner without all the spacers and crap, lol.

Thanks for the info.  Gonna do my research, I'll post my findings.  I'd rather get the longer bag now and install it now, before I wear out the springs prematurely.

EDIT: Online I found that the rear is P/N 60793.  Just got off the phone with Air Lift tech.  They said 60793 is 3" dia. and 5.5" tall.  I told them I wanted 3" longer and they said they have one 2.5" longer, and to leave 1/2" of the bumpstop on to accomodate for that difference...P/N 60756 is 3" dia. and 8" tall.  The tech also answered my question about rear flex, and he said the inside-the-coil springs are, indeed, better since they don't limit any travel...just as I thought because I have the frame-to-axle style bags like noiseyjack on my other trucks and they limit the axle droop when I put it on a lift for servicing.  Noisey's are definitely better for HUGE loads but I think if I loaded up that much stuff, that my Tracker couldn't pull it anyways  
They also said that if I provided a front ride-height measurement for the front springs, they could supply me with a part number for the front springs.  It looks like I could do rears-up-front and make it work.  I'm gonna figure that out, too, and post my findings...I'm trying to get air on all four corners right now in case I decide to put that hitch rack on the FRONT of my truck...at least I'll have front support too

What are FOA coils?  I was reading MUD CHILD's post about his fix for Calmini sagging springs and he uses FOA coils, I've never heard of them until recently...

FOA is a company out of Nevada, LV if I remember correctly. They specalize in coils springs and shocks. They list coils by size, spring diameter and spring weight so it's easy to find the correct coil and length. I run their rears and have a set of fronts I'm gonna put in, eventually.

Thanks for the info.  Gonna do my research, I'll post my findings.  I'd rather get the longer bag now and install it now, before I wear out the springs prematurely.

EDIT: Online I found that the rear is P/N 60793.  Just got off the phone with Air Lift tech.  They said 60793 is 3" dia. and 5.5" tall.  I told them I wanted 3" longer and they said they have one 2.5" longer, and to leave 1/2" of the bumpstop on to accomodate for that difference...P/N 60756 is 3" dia. and 8" tall.  The tech also answered my question about rear flex, and he said the inside-the-coil springs are, indeed, better since they don't limit any travel...just as I thought because I have the frame-to-axle style bags like noiseyjack on my other trucks and they limit the axle droop when I put it on a lift for servicing.  Noisey's are definitely better for HUGE loads but I think if I loaded up that much stuff, that my Tracker couldn't pull it anyways  
They also said that if I provided a front ride-height measurement for the front springs, they could supply me with a part number for the front springs.  It looks like I could do rears-up-front and make it work.  I'm gonna figure that out, too, and post my findings...I'm trying to get air on all four corners right now in case I decide to put that hitch rack on the FRONT of my truck...at least I'll have front support too

What are FOA coils?  I was reading MUD CHILD's post about his fix for Calmini sagging springs and he uses FOA coils, I've never heard of them until recently...

The air bags are not attach to the axle. So the axle can drop down and fully flat en out there about 2 in. The axle has just about full traval.

This is how I looked before I left last Friday, loaded to the bumpstops.  Came back and unloaded the whole rack but left my cargo in the back seat area...

DJ!! where are you going with that meat cart!  I know you want your Oregon brother to come help load it!   Don't forget to take a picture of the big butt muley you are going to put on that rack so we can all see.  PS are you going to tow your trucklet or is that some over sized tank trap breaker you have on the front?

Damn Dude! I thought I could load, you need a trailer! How's that rig do on the freeway with all that weight?

DJ!! where are you going with that meat cart!  I know you want your Oregon brother to come help load it!  Don't forget to take a picture of the big butt muley you are going to put on that rack so we can all see.  PS are you going to tow your trucklet or is that some over sized tank trap breaker you have on the front?

Come help load it...because I just returned back from a unsuccessful weekend again...but the weather seemed to affect everyone else in the area, too...it poured on us, and we only heard of one animal taken all weekend from the area.
You never know, and it's always best to plan ahead...it was the first real "drive" since I got it running, so the tow bar is just in case...actually, the real use of it is, I can hitch it up to the back of a jeep so I can help push the jeep around on the more difficult trails    seriously, though, it's for that hope-it-never-happens situation where I may need someone to tow me home.  Better to have it and not need it, than to need it and not have it

Damn Dude! I thought I could load, you need a trailer! How's that rig do on the freeway with all that weight?

That's the point...that's when we left the first time...we arrived back less than a minute later to unload all that stuff...it was riding on bumpstops and I noticed it before I even left my neighborhood.  I have a small WWII-era 1942 Bantam trailer, but it needs 2 tires...the guys at my tire shop are finding me two decent 30" or 31" tires for it.  That little trailer would be perfect, though, because it has virtually no tongue weight.
And I should have posted those pics in the Zukiworld Adventure Game but didn't get around to it.

Uh, yeah, you would have one upped me for sure! Let us know when you get the bags in. Their cake to install.

Bent; The red ride you had pictured on the ZW adventure, loaded to the hilt was what year? Wish mine was a hard top.  That picture was awesome, I only wonder how much oxygen there was left to breath in the cab of that thing.

Uh, yeah, you would have one upped me for sure! Let us know when you get the bags in. Their cake to install.

But you one-upped me because yours was properly loaded...mine wasn't hardly even drivable! 
Bags will be on hold.  Not enough time to try to install them between hunting trips...I will get them done before next season, definitely.  At least I got some part numbers available now so I know what to get and where to find them. 
Let US know if you manage to mount the rear stock length bags in the front.  If you can do it, then I know it's possible for me.  Since you already got a set it's easy for you to experiment.

Medford, mine's a 95. It was fine as long as the windows were open or the ac on Love that little rig. DJ, I keep meaning to tear into my front end, the pass side is making a bit of noise, but I just don't have the funds to replace parts or pay for an alignment right now. It's not too bad, I can live with it for awhile. I have been studying the available space and it seems there should be no reason the bags won't fit or work. The only issue I can see is how to run the air line so it doesen't get fouled. I'll figure it our eventually.

Thanks, it'd be helpful.  I didn't think about routing the air line, maybe it could be stubbed out at the top of the spring bucket (not the bottom side).
If you need funds...you could always sell that turbo setup to one of us.  I'm sure you could get at least a couple hundred bucks for it
And yes, it is extremely nice to have a tintop with AC!

Well guys, I wanted to put an update out on this:
I bought these and installed them last summer...I've been using them for the past year with no real issues, so now it's time to "report" on it.  The bags are pretty damn durable and I leave about 10lbs in them at all times.  Rides better than before.

This is a blend of installation tips and re-installation tips from last month when I reconfigured them a little bit.  I didn't have any pics of the original install so these will have to do.

I used: AIR LIFT brand, part number 60756.  They are made for a Saab model 900.  Specs are 2.5" longer than the ones spec'd for the Tracker, but with the same diameter.
FYI for those that don't know, this is going on a 1990 Tracker with 3" Calmini suspension.  That's why I could not use the stock-length ones designed for the Trackkicks.

I installed them WITH the included bumpstops (PIC 1), and ended up with this factory bumpstop/added bumpstop/air bag stacked-up mess with the back of the Tracker about 5" too high in the rear---definitely not right.  Disassambled and re-installed with factory bumpstop removed, trimmed off the "point" so a flatter surface was resting on the top of the bag (PIC 2).  
Tip: leave the bumpstops installed, mark a line where to cut "level" with the ground, then remove and cut.  The reason is because the bumpstop mounting point is not exactly level---but the top of the air bag is fairly level.  
I used a fine-toothed sawzall blade and it was easy enough then smoothed with coarse sandpaper.

I used them this way for the past year with no real issues, but I noticed that the roughly 1"dia. bumpstop surface resting on the 3"dia. top of the air bag was actually "dimpling" in the top of the air bag when some big weight was applied to them without bumping up the pressure.  The dimpling wasn't severe and in the past year it did not get any worse than I noticed when originally installed, but it was still nagging me and with hunting season coming up and me towing my little trailer around, I needed something to "spread" the load across the top of that 3"dia. air bag better...

So about about a 1.5months ago I took it all apart and did the following.  There are probably 100 different helpful suggestions some of you guys may have, such as making new bumpstops, etc...but this was my quick/cheap/easy fix and it is working well.

I used some more of my old truck mud flap material, about 1/4" thick, pretty rigid, reinforced stuff, works great for everything---including, what do you know, mudflaps (CLICK HERE FOR WRITEUP), who woulda thought?  

I cut a pattern like this (PIC 3), shaved off a bit more of the bumpstop to level it off better than I had it before, then poked a hole in the center of the rubber disc I had just cut out, inserted a pan-head screw with flatwasher through the disc (PIC 4) and tightened it against the now-flat surface of the bumpstop (PIC 5).  I also added some black roofing mastic between the two rubber surfaces to help with adhesion (just added security to help the screw).

Installed the new bumpstop assembly to the vehicle (PIC 6).  Put everything back together and the diameter of the rubber disc clears the I.D. of the spring coils (PIC 7).  Load/weight is distributed more evenly across the top of the bag.  This has been working for over a month now and I don't see any issues with it.  
I DID consider the metal screw head rubbing on the top of the bag---but the bag has some raised lettering across the top.  It's gonna take years of scuffing to even get through that tough stuff...

More pics of installation.  This is how I originally had the air lines routed, but I didn't post on it until I had a chance to try it out.  No issues reported here.
Drilled hole (I think 5/8"dia) in bottom spring support for air line to run through.  I was going to add a grommet but it would not stay put on that thick metal---I deburred the hole.  No problems
I protected the supplied rubber air line in convoluted tubing ("wire loom").  I found these little aluminum clips that I was able to mount using the brake line mounting bolts, to hold the air line/tubing in place with the brake lines (you can see these in the pics right below the spring cups).  
I routed the 2 lines to where the diff breather is, and that is where I installed the "T" fitting.  Then secured with zip ties to the diff breather (since I know that is the proper length as it has never stretched/pulled out).  
...then over the fuel tank to the rear, routed through the factory grommet where the taillight wiring goes through to the right taillight...
Removed taillight and drilled hole in fuel filler area---hidden, protected, and works great.  Careful, make sure it will fit your inflation valve, as I have a few around my house that don't fit in there with the gas cap on, I have to either use a different filler valve or remove the fuel cap.  Aggravating, but I plan to have an onboard compressor with an inline valve for these bags soon.

Hope this helps the next guy with his installation!