Where to put the spare tire

[Wayne Sihler]

depends on the size of the tire. :wierd:

Ok,it must depend on the volume in the tire insted of the psi? :doh:
Wayne

 

[BrentNClemson]

Ok,it must depend on the volume in the tire insted of the psi? :doh:
Wayne

Volume AND psi!

 

[Willis]

So now we know 2 good reasons not to use your cage as an air tank:

The obvious one:
It could explode if you roll,

And the new one:
Adds to your center of gravity (since your filling the tubes above your head too)

 

[XJZ]

I just tried to weigh some air on the bathroom scale and didn't get a reading. Am I doing something wrong? :dunce:

 

[CaptTrev]

I just tried to weigh some air on the bathroom scale and didn't get a reading. Am I doing something wrong? :dunce:

Are you sure you payed the gravity bill this month? :laugh2:

 

[Phil]

Right now I've got it on the back just above the bumper, but I've hit it a few times dropping off of embankments and on rocks. I'm fixing to go from 30s to 33s and this will only get worse. I'm not concerned about getting stuck because of its location, but I am worried about bending the mount or the rear deck when I hit it. I've thought about putting it on the roof, but that raises the center of gravity and makes it kinda' hard to get to. Of course putting it inside takes up room.

So far I've ruled out just about any place that I can think of to put it! Any ideas? Where do you keep yours?

(After reading the whole thread) Put it in the bed. :moon:

 

[Beezil]

okay, I wanna know which one of you asshats can be quoted as saying a rollcage used as an airtank can explode...

okay, who was it!? uke:

 

[XJguy]

Keep it on the roof for daily use...when you go wheelin' throw it inside and tie it down.

XJguy

 

[Willis]

okay, I wanna know which one of you asshats can be quoted as saying a rollcage used as an airtank can explode...

okay, who was it!? uke:

It's just common sense, everyone knows it

I'm going to build mine with a quick release, so when I start to roll, I can release the air, hereby lowering my center of gravity and possibly preventing the roll, and prevent explosion if I do go over.

:laugh2:

 

[What Rd]

I'm going to build mine with a quick release, so when I start to roll, I can release the air, hereby lowering my center of gravity and possibly preventing the roll, and prevent explosion if I do go over.

:laugh2:

Now here's some fresh thinking! Even better, if you put discharge ports facing various directions, at the moment a roll seems innevitable you simply throw the appropriate remote-controlled quick release and the jet of compressed air will not only eliminate the impending explosion :explosion: and get all that heavy air out of the overhead tubes, but will also propell the Jeep back onto all fours!

Now, let's see. How much weight are we saving by carrying our rooftop spare all nice and flat? Given that one square inch of Earth at sea level has about 14 pounds of air pushing down on it, and that that column of air extends some 25 miles high (granted it gets a little thinner as you go up), that would make the weight of air in a 33x12.50 compressed to 30 psi weigh . . . roughly . . . a coupla ounces (maybe?). I don't know why I'm not already doing this! :doh:

 

[BrettM]

Now, let's see. How much weight are we saving by carrying our rooftop spare all nice and flat? Given that one square inch of Earth at sea level has about 14 pounds of air pushing down on it, and that that column of air extends some 25 miles high (granted it gets a little thinner as you go up), that would make the weight of air in a 33x12.50 compressed to 30 psi weigh . . . roughly . . . a coupla ounces (maybe?). I don't know why I'm not already doing this! :doh:

YEAH! see that's the reason everyone airs down, to lose that extra weight! personally, I don't buy it, I'm going to just build a stronger drivetrain to cope with the extra weight of running my tires at 60psi on the 'Con.

 

[Rev Den]

At 48F a 33 X 12.5 tire weighs 4 oz more with 28 PSI of air in it.


Rev

 

[ZPD]

Ok you all are :looser:s
This is the only way to do a spare
http://www.xjworld.4wdriver.com/tirecarrier/tc.html

It even raises up even higher now. It is well out of the way while on the trail and provides reaonable rear window viewing for the daily driving.

 

[MaXJohnson]

JUNK MATH - :dunce:

Estimating the 33X12.50 tire volume (as a torus)

R=1025, r=6.25

volume = ~7900 cubic inches

= 4.995oz @ 14 psi & 9.99oz @ 28psi

 

[XJWheelie]

Robert -
You think getting a 33 up onto the roof rack would be difficult?
I have a hell of a time just getting my 33x10.50 BFG KM from the ground into the back end where it rides laying flat. The hard part is getting it from the ground into my lap without pulling myslef outta my chair. Once there I can lift it in easily enough.
To me, difficult implies that something can be done. There is no way on Earth I could get a spare onto my roof - let alone get one down. It's just too high to reach from a chair. I like mine inside despite the amount of room it eats. When I go bigger, it'll have to ride on a bumper carrier because the 33 is all that will fit inside with the seat up (need the passenger space). I have a couple of ideas running through my head for a carrier that will not only extend up to improve departure angle when wheeling, but also pivot down so that I can mount the tire while it sits on the ground and then crank (or reel or jack or ?) the whole thing into an upright position and lock it down.
Cool, huh?

I'm in a wheelchair too, but I cheat when it comes to getting to the spare tire. When I'm on paved roads I have a service with my cellphone company that'll change my tire for me. When I'm off road I've got some REALLY GOOD FRIENDS that'll take care of that if the need arises. One reason that I'm going to a Dana 44 rear end; they're good friends, but if I break an axle and have the wheel, drum, and what's left of the axle roll down a 50 foot embankment I may not have any friends that are that good!!!

I'm definitely interested in your up & down tire carrier. Please keep me up to date on it.

 

[XJWheelie]

Ok,it must depend on the volume in the tire insted of the psi? :doh:
Wayne

Ok, I've got the solution to this delima. Get a temporary spare out of a Geo Metro and drill out the center of the rim to match the Jeep's lug bolt pattern! That way I could put it on top and the CG wouldn't change as much, but the 45 psi of air might throw a wrench in that equation!!!

 

[Wayne Sihler]

JUNK MATH - :dunce:

Estimating the 33X12.50 tire volume (as a torus)

R=1025, r=6.25

volume = ~7900 cubic inches

= 4.995oz @ 14 psi & 9.99oz @ 28psi

I told my daughter last night that some one would figure the weight of the air in the tire.
All you have to do is issue the challenge-----Good Work :wave1:
Wayne

 

[XJWheelie]

One last thought. Why not just put 4 spare tires on the roof seperated by 2 lightweight axles and then the CG wouldn't be a problem. If you roll over just get out and push it down the trail!

 

[buster]

Just mount it on the hood or front bumper or both.

 

[Rev Den]

JUNK MATH - :dunce:

Estimating the 33X12.50 tire volume (as a torus)

R=1025, r=6.25

volume = ~7900 cubic inches

= 4.995oz @ 14 psi & 9.99oz @ 28psi

At what temp??


Rev