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Q for Diamond & Others

Submitted: Thursday, Jul 03, 2003 at 21:50

Member - Cocka

I'm carrying a couple GY Wranglers 285/75 tyres as spares.
I want to over inflate these as spare air tanks and have an air transfer hose.
The tyres are marked with a max air pressure figure but I think that that is only when they are under load, I wouldn't be using them on the highway with anything other than the usual recomend pressures. So -
What is the max pressure (psi) to which you can inflate a tyre for the purpose of storing backup air ?? Carpe Diem
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ThreadID: 5799 Replies: 6
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AnswerID: 24146   Submitted: Thursday, Jul 03, 2003 at 22:02

Truckster (Vic) replied:

You can get a truck air tank for $20 from truck wreckers. Much much safer and will do more... if your keen you can have it connected to your onboard compressor and have endless high pressure, which is a hell of a lot safer.

There was a post on one forum about a tire exploding on a bloke that was overinflated, luckily nobody was killed, it went off late in evening. He soon became center of attention in the camp ground!

YMMV.

Reply 1 of 6
FollowupID: 16249   Submitted: Thursday, Jul 03, 2003 at 22:53

Member - Cocka posted:

I guess that's why I'm asking the Q. The Q should say "safe maximum p" . Any ideas 70-80-90- ??Carpe Diem
FollowUp 1 of 4
FollowupID: 16251   Submitted: Thursday, Jul 03, 2003 at 23:12

Truckster (Vic) posted:

What is the max on the sidewall? Check there first.

Usually around 60psi aint it? depending on tire and brand and size model etc..
FollowUp 2 of 4
FollowupID: 16255   Submitted: Thursday, Jul 03, 2003 at 23:26

Member - Cocka posted:

read my lips - I said the tyres are marked with a max pressure but .......... ........ .........
It's 70psi.Carpe Diem
FollowUp 3 of 4
FollowupID: 16256   Submitted: Thursday, Jul 03, 2003 at 23:37

Truckster (Vic) posted:

Then 70 would be the safest .. Wouldnt it?

When they fit tires, they go upto 100psi to bead them on the rims sometimes, thats only for a minute, then they deflate the tire... but most modern tires I've seen dont need anything like that.

You may put 70psi in the tire, but if your out in the sun, its going to get hot and expand, and its your call what you do. Theres dudes on patrol list runnin 120psi in spares for some reason...Crazy to me.. So you get a flat tire or 2 and you lose your 'air tank'...

The price of doing it right, and having seen personally the damage an exploding tire can do to a body (although that was a truck tire not a 4wd), I'll go the small tank (good for beading tires) $20 + bracket, and fittings $50 tops option.

You can get a tank big enough to inflate 4 tires for around $60 at truck wreckers, Nick got another one the other day for his GQ.
FollowUp 4 of 4
AnswerID: 24169   Submitted: Friday, Jul 04, 2003 at 07:54

Member - Wherethehellawi replied:

Cocka, If the tyre says 60 then its 60.
If any one tells you its 90 and the tyre explodes injuring you or, god forgive, anyone else who is going to responsible???

Hell there is no test pressure rating on the things so I suggest that one sticks with the pressure as rated.

Richard
Reply 2 of 6
AnswerID: 24177   Submitted: Friday, Jul 04, 2003 at 10:08

Member - Rohan K replied:

Cocka, a couple of months or so ago one of mags (4x4 Monthly, I think) did a story on making your own air "gun". They talked about using the tyre as the air tank. They ran the tyre at 100 psi but I think they only pumped it up to that just before using it.

I'm with Truckster though, exploding tyres scare me. I saw one let go in a tyre shop once. It blew the guy clean across the workshop (about 30 feet). Thankfully he wasn't badly injured but I've seen photos of the results of exploding tyres that would scare the bejesus out you - impressions of human bodies made in solid concrete - Yuk!Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)
Reply 3 of 6
AnswerID: 24183   Submitted: Friday, Jul 04, 2003 at 11:52

Member - Wombat (Vic) replied:

Cocka,

Please don't even entertain the thought. There's a brand new grandchild out there who would like the benefit of the knowledge and insight that only a grandfather can give. With all due respect - buy a pressure tank instead."Live today as if there may be no tomorrow"

Wombat
Reply 4 of 6
AnswerID: 24198   Submitted: Friday, Jul 04, 2003 at 13:41

diamond (bendigo) replied:

gday cocka.
i have to agree with all above.
10-20psi over highest pressure marked on side wall wouldnt be a problem.we sometimes pump tyres up to 120 psi to seat the beads but thats with me standing out side the back door just in case it blows.
when they go they go big time.looking foward to september(landcruiser park/fraser island)
Reply 5 of 6
AnswerID: 25793   Submitted: Thursday, Jul 24, 2003 at 15:22

dave slater replied:

Hi Cocka,
The only thing I know anybody did with spare tires as compressed air source was Volkswagon. They used them to power the windsheld washers. Don't know if they still do that or not.
There is an amazing amount of energy stored in compressed gas, tires included.
later, slater
Reply 6 of 6