255/75-17 Silent Armor & 1.75" Smaxx numbers

[Harry Moto]

I finally threw down and got my tires, the 255/75-17 Silent Armor. I was going to get the 245/75, but they were over $200 per, while the 255/75 were well under $200. It seems the 255/75 is OEM on a Jeep of some kind, so they make a lot more of that size than the other. Seemed like a good compromise!

So, first the numbers: These are all taken from the garage floor to the fender at the top of the wheel well, keeping the tape straight up and going through the centerline of the wheel. I've included the numbers for stock, with airbags in the rear springs, with the 1.75" Smaxx lift, and finally with the new tires. Everything starts out bone stock, tires were 245/65-17 Michelins.

.........................................................................Rear...................Front...................AVG........AVG
.........................................................................LR..........RR..........LF.........RF..........Rear.......Front
Stock, 245/65-17...................................................34.0.......34.4.......33.0......32.9.......34.2........32.9
245/65-17 with 35 psi in rear air bags ..........................34.5.......34.8.......33.0......32.9........34.6.......32.9
245/65-17 with 5 psi in rear air bags (normal setting)........34.1.......34.5.......33.0......32.9.......34.3........32.9
1.75 Smaxx, 245/65-17, 5 psi in bags ..........................33.9........34.5......34.0......34.1........34.2.......34.1
1/75 Smaxx, 255/75-17 Silent Armor, 5 psi in bags...........35.5........35.8......35.5......35.5........35.6.......35.5

Clearance is good, I'm using 1.25" spacers and the only lift is the Smaxx 1.75" spacer in the front. On some steep downhill switchbacks we could hear the tires rubbing the inner fender, but that was the only time. Don't hurt nuthin', if ya know what I mean.

The truck is right where I want it now, except that I'm going to add the OEM air springs in the back with an onboard air compressor and tank with valves for direct manual control. After I remove the dealer installed nightmare wiring alarm. And install the rear-view camera... and the front view camera... and the overhead console... and the sun visors... etc.

Pix or it didn't happen, right? Next post!

[Harry Moto]

So far I've been unable to upload the pix. They're the same size as the ones I posted for my trail ride post, and the file size is smaller, but I get an error message; "Sorry, the board attachment quota has been reached.". I've got 5 pix to put up, one showing the tire clearance with the fender, one showing the profile (they don't stick out past the sides of the truck), one showing clearance with the Upper control arm, and two 'scenic's showing the truck profile with lift and tires. I can put these on my website, but that won't happen until my weekend starting next Wednesday. Or later: we're celebrating our 20th this coming weekend. 8^)

[HARDTRAILZ]

So the smaxx 1.75 barely gave you an inch of lift...interesting.

[Trail X]

So far I've been unable to upload the pix. They're the same size as the ones I posted for my trail ride post, and the file size is smaller, but I get an error message; "Sorry, the board attachment quota has been reached.". I've got 5 pix to put up, one showing the tire clearance with the fender, one showing the profile (they don't stick out past the sides of the truck), one showing clearance with the Upper control arm, and two 'scenic's showing the truck profile with lift and tires. I can put these on my website, but that won't happen until my weekend starting next Wednesday. Or later: we're celebrating our 20th this coming weekend. 8^)

Sorry, my fault! I didn't realize we met our limit on the board settings. You should be good to go now.

[Harry Moto]

Cool, thanks! Back in business!

So, first of all, clearances. These are with GoodYear Silent Armor 255/75-17, 1.75 Smaxx, 1.25" spacers. (grinding the studs, yes.)

[Harry Moto]

And this is how it looks. Pegged the look I was after, it's a stock looking thing, but has a great deal more clearance and capability than the stock truck. Quiet, very smooth (poofy) ride, but doesn't touch down when we go exploring. Perfect. almost...

[Harry Moto]

So the smaxx 1.75 barely gave you an inch of lift...interesting.

I found that interesting as well. Also, the air bags deliver very little lift. I use them when I load the back up with weapons and ammo for a shooting trip, but you don't get all of your ride height back. This last trip I aired them up to 30 psi, still 1/4" down from unloaded/5pis. Out on the trail I let them down to 20 psi, and that helped the ride a lot but we lost more ride height.

My numbers are all taken in the garage, parked in roughly the same place. There are some variations as the garage floor is a little 'lumpy', but everything is within an eighth, certainly. I'm measuring from the floor to the bottom of the fender in the center of the fenderwell, going straight up and through the center of the wheel/tire. Their advertised numbers may be taken somewhere else, maybe with a different procedure?

The solution to the rear ride height issue is sitting in the garage: I have a set of OEM airbags, brand new. The feed line is 1/8" instant fitting, I'm going to drill it out and go to at least a 1/4" line. The plan is to have an onboard air system with nupro style valves for control. Then I can adjust ride height from the drivers seat as desired. The advantage, besides always pegging your ride height, is that you can hook up your trailer effortlessly. Lower the back, look the ball right under the hitch with the rear view camera, then raise the back to put the ball right into the socket. Fun stuff!

[chevycrew]

Can you add a spacer above or below the rear air bag to allow it to be taller when inflated? Sounds like the bag is too short to get any lift when fully inflated.

[Trail X]

Looks great Harry! I love that moon photo, my wife and I were enjoying some moon gazing the other night too.

[Harry Moto]

Can you add a spacer above or below the rear air bag to allow it to be taller when inflated? Sounds like the bag is too short to get any lift when fully inflated.

The bags do look too short. I got the recommended bags for our trucks, don't remember part numbers or any of that. When the truck is sitting on the springs the bag pretty well fills the space, but with the truck on a lift the bags definately dangle in the middle. Looked like 2 or 3 inches from the bottom of the air bag to the end of the space in the spring. I think the right answer would be a longer air bag, but maybe there's a problem with that? The bags I had on my Dakota were free-standing, not trapped inside the coil spring. They lifted the back enough that I could deflate them, back the ball under the trailer hitch, then add air and put the ball all the way into the hitch. The TB setup doesn't come close.

Jim, it was a great night for moon-gazing, fo sho! Glad you like the pic!

[Trail X]

The bags I had on my Dakota were free-standing, not trapped inside the coil spring. They lifted the back enough that I could deflate them, back the ball under the trailer hitch, then add air and put the ball all the way into the hitch. The TB setup doesn't come close.

I think the inside spring bags aren't really meant to add lift, just make the spring stiffer, which helps a ton when hauling heavy or variable loads.

Curious, are the two bags separate - or connected by an airline?

[Harry Moto]

They can be run separate, but I have them T'd to a single schrader valve out back. Ultimately it'll be onboard air etcetera, and when I install all that mess I'll have a separation valve so the air springs can be connected or not.