Tyre Pressure Drop - porous rims?

MartinK · Dec 1, 2008

My 2002 td5 seems to be dropping tyre pressure over time - and dropping faster than would seem "normal". My rear tyres both dropped by almost 10psi over the last 2 months. Indeed this year I have needed to top-up pressure quite a few times, and it seems to be getting worse... All pressures dropped a bit, only the front drivers side stayed anything like. The tyres are part-worn BFG AT, I don't think I have a "normal puncture".

The polar "alloys" are in good condition on the outside.

The only guess I have is that corrosion is allowing the rims to become porous, and leak slightly. Looks like I need the rims re-finished.

Anyone else had similar issues? If so, what was the fix?

Trewey · Dec 1, 2008

I'd get the tyres taken off, the rim beads cleaned up, new valves fitted and then see how it goes.

ratty · Dec 1, 2008

MartinK said:
My 2002 td5 seems to be dropping tyre pressure over time - and dropping faster than would seem "normal". My rear tyres both dropped by almost 10psi over the last 2 months. Indeed this year I have needed to top-up pressure quite a few times, and it seems to be getting worse... All pressures dropped a bit, only the front drivers side stayed anything like. The tyres are part-worn BFG AT, I don't think I have a "normal puncture".

The polar "alloys" are in good condition on the outside.

The only guess I have is that corrosion is allowing the rims to become porous, and leak slightly. Looks like I need the rims re-finished.

Anyone else had similar issues? If so, what was the fix?

the cheapest fix is to keep adding free air until the problem gets bad enough to need to do something about it. I had the same problem on a steel rim caused by rust. When it got to the point that I had to reinflate it weekly I removed the tyre from the rim. Wire brushed the rust and dabbed some paint on it. It's been fine now for 9 months.

sounds more like a valve problem on yours if the rims look to be in good condition.

hughesy · Dec 1, 2008

10psi over two months is hardly what I'd call a problem.

MartinK · Dec 1, 2008

hughesy said:
10psi over two months is hardly what I'd call a problem.

Well, 1psi per week is basically what it is I guess.

That's 1 psi more than it should be! :scratching_chin:

Wanagetmuddy · Dec 1, 2008

MartinK said:
Well, 1psi per week is basically what it is I guess.

That's 1 psi more than it should be! :scratching_chin:

Well In my opinion you should check your tyres once a week.

I have never had a set of wheels and tyres in any vehicle that has stayed the same pressure for two months.

It does go down specially if you ramp it on the curbs.

My tyres actually do go down if you do a lot of laning the mud gets trapped along the beads and slowly lets the air out as some have suggested

MartinK · Dec 2, 2008

Yes, I guess I'll just check the pressures more frequently until (if) it becomes a bigger problem. The BFG AT's have been on the Disco for around 3 years now, and the pressures always stayed there or thereabouts - until the last few months when I've noticed this pressure drop on 3 wheels. The recent issue with losing pressure has bothered me. The posts on this forum suggest there's not a "known" problem with LR Polar Alloys. I'll pump them up regularly through winter and monitor the situation... If it persists I'll get the wheels refinished (blasted, refinished, new valves and rebalance) in spring when the salt's gone...

Wanagetmuddy · Dec 2, 2008

MartinK said:
Yes, I guess I'll just check the pressures more frequently until (if) it becomes a bigger problem. The BFG AT's have been on the Disco for around 3 years now, and the pressures always stayed there or thereabouts - until the last few months when I've noticed this pressure drop on 3 wheels. The recent issue with losing pressure has bothered me. The posts on this forum suggest there's not a "known" problem with LR Polar Alloys. I'll pump them up regularly through winter and monitor the situation... If it persists I'll get the wheels refinished (blasted, refinished, new valves and rebalance) in spring when the salt's gone...

Sounds like a good plan

I have machs on mine they still go down only had them on for about 6 months

discobasher · Dec 2, 2008

Personally I check my tyre pressures weekly along with oil level and coolant etc. I was in the tyre trade a few years back and as suggested before it will more likely be the lacquer lifting from the inner bead causing a slight leak. If you really want to find out take 1 of the offending wheels off and poor some soapy water around the tyre bead and see if it foams. It will only be very fine but it will prove your leak.

david451 · Dec 2, 2008

discobasher said:
Personally I check my tyre pressures weekly along with oil level and coolant etc. I was in the tyre trade a few years back and as suggested before it will more likely be the lacquer lifting from the inner bead causing a slight leak. If you really want to find out take 1 of the offending wheels off and poor some soapy water around the tyre bead and see if it foams. It will only be very fine but it will prove your leak.

Dont bother taking them off, just use a scooshy bottle with soapy water in it, used that method all the time especially for air leaks on trucks, give the tread a scoosh as well.

Mine all **** air, the original tyres were glued on and when I fitted the off road ones the tyre fitter was sweatin like a rapist, cleaned them up fitted the tyres and they **** air. Crap alloy

Tyre Pressure Drop - porous rims?

MartinK

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Trewey

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ratty

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hughesy

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MartinK

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Wanagetmuddy

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MartinK

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Wanagetmuddy

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discobasher

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david451

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