BJ spacers; tire- UCA clearance
12-05-2008, 01:18 PM
#1
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BJ spacers; tire- UCA clearance
Will I still be able to air down my 31s without the sidewall contacting the UCA? Could I still run snow chains? Can I clearance the edge of the UCA (the part that might contact the tire) without structurally compromising the A-arm?
12-05-2008, 02:01 PM
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When I had stock wheels and BJ spacers on my truck there was a bout 1/4" clearance between the tire and the UCA at ride height and the tires contacted at full droop so I'm inclined to say no.
Wheel spacers are always an option if you want to keep running stock wheels
Wheel spacers are always an option if you want to keep running stock wheels
12-05-2008, 03:30 PM
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maybe
you should be able to air down since the rim is suspended (hanging) from the top of the tire: releasing air pressure will cause the bottom to bulge, not the top (generally speaking) odd tread widths and rim sizes may bulge at the top as well.
you will likely not be able to use chains with stock offset/backspacing tires as mrmatson mentioned. at lower speeds, the traction section of the chain being spun outwards by centrepital force will not apply sufficient tension to the sidewall section of the chain to guarantee it will ride against the sidewall. make sense? considering chains are usually 1/4 - 1/2" (depending on the construction), 1/4 between the tire and UCA is obviously not enough.
you may be able to grind off the "lip" around the UCA without compromising the strength of it, but I would not grind much more than that off
you should be able to air down since the rim is suspended (hanging) from the top of the tire: releasing air pressure will cause the bottom to bulge, not the top (generally speaking) odd tread widths and rim sizes may bulge at the top as well.
you will likely not be able to use chains with stock offset/backspacing tires as mrmatson mentioned. at lower speeds, the traction section of the chain being spun outwards by centrepital force will not apply sufficient tension to the sidewall section of the chain to guarantee it will ride against the sidewall. make sense? considering chains are usually 1/4 - 1/2" (depending on the construction), 1/4 between the tire and UCA is obviously not enough.
you may be able to grind off the "lip" around the UCA without compromising the strength of it, but I would not grind much more than that off
12-05-2008, 03:50 PM
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I wasn't thinking of that, airing down meant the bottom bulges (duh). I've heard you say the tire hangs from the rim before, and I don't follow, could you explain this to me?
12-05-2008, 04:26 PM
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It's fairly difficult to describe...
https://carnot.physics.buffalo.edu/a.../msg00089.html
https://carnot.physics.buffalo.edu/a.../msg00089.html
12-05-2008, 04:32 PM
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comes back as ' carnot.physics.buffalo.edu uses an invalid security certificate.
The certificate is not trusted because the issuer certificate is unknown.
(Error code: sec_error_unknown_issuer)
lee
The certificate is not trusted because the issuer certificate is unknown.
(Error code: sec_error_unknown_issuer)
lee
12-05-2008, 04:33 PM
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Re: [Phys-l] Another tire question
--------------------------------------------------------------------------------
From: "LaMontagne, Bob" <RLAMONT@providence.edu>
Date: Fri, 9 Nov 2007 12:43:55 -0500
--------------------------------------------------------------------------------
Is this another case of talking past each other? I assume that what we
are calling the "bead" is simply the collar that contacts the rim of the
tire. If that assumption is correct, then the collar "hangs" from the
sidewall (which I assume is the visible side portion of the tire when it
is on the wheel.) I think the hangup here is trying to envision how a
"bead" which cannot physically grab the wheel can exert an upward force.
The sidewall certainly can pull the collar (bead?) up - and the collar
(bead) really becomes part of the rim after mounting simply because of
tension pulling it against the rim since it is acting like a taut
elastic band. The bead acts like a sling but with a radially inward
tension acting on its entire circumference. The upper sidewall pulls up
on this sling.
Bob at PC
...
--------------------------------------------------------------------------------
From: "LaMontagne, Bob" <RLAMONT@providence.edu>
Date: Fri, 9 Nov 2007 12:43:55 -0500
--------------------------------------------------------------------------------
Is this another case of talking past each other? I assume that what we
are calling the "bead" is simply the collar that contacts the rim of the
tire. If that assumption is correct, then the collar "hangs" from the
sidewall (which I assume is the visible side portion of the tire when it
is on the wheel.) I think the hangup here is trying to envision how a
"bead" which cannot physically grab the wheel can exert an upward force.
The sidewall certainly can pull the collar (bead?) up - and the collar
(bead) really becomes part of the rim after mounting simply because of
tension pulling it against the rim since it is acting like a taut
elastic band. The bead acts like a sling but with a radially inward
tension acting on its entire circumference. The upper sidewall pulls up
on this sling.
Bob at PC
...
Last edited by abecedarian; 12-05-2008 at 04:35 PM.
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12-05-2008, 04:42 PM
#9
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I am fairly confident that the tire sidewall will clear, but I question whether chains will clear. For chains to clear, there needs to be about 1/2" clearance I would think.
12-05-2008, 04:50 PM
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Thanks Abe.
12-05-2008, 06:10 PM
#11
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Matt16,
Take this as advice only as I don't have the same issues you do but you could, in theory, grind the lip off of the UCA and then weld in some supports across the top of the UCA on either side of the BJ area to maintain some strength. I would like to point out here that the amount you'd have to grind to run chains isn't a good idea. I mean you have the Aussie in the rear and you could put chains back there and probably get almost anywhere in 2X that most others can't get in 4X.
Just a thought or two that I hope helps.
Take this as advice only as I don't have the same issues you do but you could, in theory, grind the lip off of the UCA and then weld in some supports across the top of the UCA on either side of the BJ area to maintain some strength. I would like to point out here that the amount you'd have to grind to run chains isn't a good idea. I mean you have the Aussie in the rear and you could put chains back there and probably get almost anywhere in 2X that most others can't get in 4X.
Just a thought or two that I hope helps.
12-05-2008, 06:24 PM
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Ok, I'll bite. It seems that you could look at it either way, but the way it was explained there works for me. The idea of the truck "hanging" from the rim mislead me, but I the idea of the bead acting as a sling of sorts which suspends the rim explains it well.
Thanks Abe.
Thanks Abe.
simply put, the air pressure keeps the tire somewhat round and the bead hangs from the sidewall, and the rim is held by the bead, and the rim holds the truck up.
if the bottom of the tire was holding the bead up, the bulge, the slack in the sidewall, would be at the top
Last edited by abecedarian; 12-05-2008 at 06:28 PM.
12-05-2008, 06:26 PM
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12-05-2008, 06:40 PM
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