Lesson learned

When I inherited my tractor I also received a pressure gauge to check the water filled rear tires. A couple of weeks ago I had a rear tire blowout. It sounded like a gun went off in my ear. The the ambient temperature was a little over 100, I hit a bump and boom the tire went with an 8 inch gash in the side wall. Long story short, I thought that I was putting 20 PSI in the tire COLD. Upon checking against a know good gauge my gauge did not even budge until over 30psi. I measured the temperature of the tire in the sun it was 160 degrees. So with the water filled tire, excess air pressure, and extreme heat the tire gave way. I have replaced both rear tires (air only now).
The moral of this is don't trust old gauges, check their accuracy or replace them.

you can tell by just looking at the sidewall flex and how the treed makes contact with the road . i run 8 to 10 lbs dry

10-15 PSI is about max for 90% of tractor rear tires. Only time one might need to go higher is the seat the beads and even then one should not go over 30PSI

Yes, every gauge is a little different, and some a lot, as you found out!

To be REAL here, likely the old tires were old and ROTTEN.

NOT sure how you measured the pressure AFTER the tire blew???

Don't just assume that brand new shiny gauge you just got is accurate either.

We were driving the snowplow truck into town a few years back when one of the tires had a flat. The spare was also low. When we got to the tiny little blip-of-a-town called Greenbush, MN, we stopped in the local auto parts store. I bought a brand new, shiny, nice long truck tire gauge (used with dually's). I tried it out in a bit of a hurry and just thought I was tired, as the reading seemed way off on the now-new tires. Well, I put the gauge away and forgot to check accuracy.

Then a year or so back, went and bought a used skid loader. After getting the loader on the trailer, I wanted to check air pressure in all tires. So, got out my nice, shiny, new trucker's gauge! I wasn't reading anything from the rear air suspension bags - figured it wasn't sagging much, so must be OK, yet too little pressure for this gauge to register. So next I went to the driver front wheel. The gauge was reading less than 10PSI!! :shock:

Hmm, that can't be - the tire is fully inflated. So I went to read the rear tire. It's got more weight on it. Surely IT will register better! Nope....not even 10PSI. The gauge was faulty. The guy I was buying the loader from went in his shop and hauled out a large wheeled air compressor - and let me tell you, it was hot that day! He handed me a cheap all-plastic tire gauge and I checked my tires. They all read exactly what I put them at prior to leaving the house!!

Guess what I'm using now? A cheap, all-plastic tire gauge!

Just to clarify, the tires on my tractor were R4 backhoe/ loader tires about 10 years old but garage kept when not in use. The Manual for this tractor calls for 20 psi in the rear tires. I believe that in order to have been as loud as it was it had to have been an over pressure condition.
I compared the reading from this gauge to a dial air gauge using a truck tire. I realize that I was comparing an air to liquid fill gauge. However pressure is pressure, and the liquid gauge did not respond to anything below 30 psi.

I have several gauges and buy new off and on. I run a lot of tires around 10 psi more and less for a soft ride and need a low pressure gauge for that and
higher for other applications. I know that one time I ruined a gauge on a CC filled tire forgetting it was filled and not paying attention to the fact that the
stem was at the lower half of the tire when checking.

Practice now is to ensure the valve is at Noon and blow out a little air before testing. On values, I have compared readings over the years and find that they
are really pretty accurate for something cheap.

I was tought years ago when checking fluid filled tires after checking put guage in water and pull the reading stem in and out several times to flush out the fluid so it does not make the guage stick. Not a bad idea after doing that use air pressure to dry out guage. This was years before I ever heard of a dial type guage, must have been over 50 years ago. And I would have been close to my mid 20's at that time. Also some guages are fluid rated but miost are not. Don'y think I tried a guage on any fluid filled tires in over 30 years, just eyeball the tire.