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Probably a dumb (tire) question, but y'all should be used to that....
- Thread starter TruckinThumper
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Could you give a rough example of load vs pressure in your application, what kind of trailer are we talking about here?
UglyViking
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I can't believe there are all these comments and not a single person recommended chalking the tires.
It may be a little overkill but this is something that pretty much anyone that adds larger tires and wants a good ride does, or at least should.
Basically, you drive to an area that has flat pavement (empty parking lot for example), add a heavy amount of chalk to about a palm width of tire lugs for each tire, drive about 30 ft or so, and check the lugs to see how the wear pattern looks. You can continue adjusting down till the chalk is basically evenly worn across the tire and that's going to gain you the best ride (and theoretically longest tire life) that you can have. Oddly enough, CJC offroad just did a video on this the other day you can check out (youtube link).
It may be a little overkill but this is something that pretty much anyone that adds larger tires and wants a good ride does, or at least should.
Basically, you drive to an area that has flat pavement (empty parking lot for example), add a heavy amount of chalk to about a palm width of tire lugs for each tire, drive about 30 ft or so, and check the lugs to see how the wear pattern looks. You can continue adjusting down till the chalk is basically evenly worn across the tire and that's going to gain you the best ride (and theoretically longest tire life) that you can have. Oddly enough, CJC offroad just did a video on this the other day you can check out (youtube link).
jetrinka
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The above chart is a good example. For instance the 3500 gross single axle utility trailer I have I really only need to run 50 PSI in the tires to achieve a load rating exceeding the gross of the trailer. Just have to be wise about not overloading it. No need for max pressure listed on the sidewall.
A bit different with the truck IMO because I am not operating under the assumption my truck is going to be constantly laden down like my trailer probably will be - but the tire size on my truck doesn't offer any more load capability at its max pressure of 80PSI than it does at 65PSI so why run the max. Its apples to sort of apples I guess..
When I had 35"s on the truck I could run MUCH lower pressures and still achieve proper load ratings. IIRC I ran something like 45 PSI in the front and high 30's rear. Tires wore great, made a flat contact pattern and were never overloaded.
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Chalking, IMHO, isn’t overkill it’s out dated. Scales and charts are much more accurate. I used to chalk tires before internet charts were common, really before internet took off. It worked good.
@jetrinka the problem with chalking tires that are too wide for a rim is that you can end up underinflated. It’s why rim width is rather important.
We would use the tire load math and then chalk it. Tire load math also works, but at lighter load is still sometimes more air than needed, but that’s better than less air.
For those that haven’t don’t math based on the side wall it’s pretty simple. 0 lbs at 0 psi and 3640 lbs at 80 psi, that’s 45.5lbs per psi. Using the scale weight I had yesterday of 6,220 on the rear I’d take 6,220/2 = 3,110 then 3,110/45.5= 68.3 psi. I’d use 70.
Compared to the load and inflation tables, which states I need more than 65 but less than 70 psi, but closer to 65. I’d run 70. Pretty close considered I’d end up at 70 on both examples.
Now on the light side my empty RAW is 3400. Tire math tells me to use 38.5 psi, but the I’m under the minimum chart pressure of 35 psi for a load of 2020. On the highway I’d run 35 empty, Jr around town in the winter I drop to 30.
On my TJ, with 31’s, the minimum chart pressure is 25 but I don’t run that unless I’m going to leave town and hit the highway. I typically run 18-20 summer and 14-15 winter. Tire math calls for 19 with just me in it.
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There can be. My trailer has D rated ST trailer tires. Max pressure on the sidewall is 65psi. But the owners manual for the tires says you can run them up to 75psi to change the max speed from 65mph to 75mph. They stress that 75psi does not change their max load capacity. Since I'm often pulling on interstates with a 75mph speed limit, I always air them up to 75psi to be safe.
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Which tires are those?
My Goodyear marathons were capable of that, which I did a couple times. They were also loaded at about 90% so not grossly overinflated.
AFIK the marathon is discontinued and they should all be off the road by now due to age. Should… I’ll bet there are still plenty out there and blowing out often from age.
Marathon's were made in China and a horrible tire.
I run Endurance on my 5th wheel and boat trailer and love them. If I was running ribbed tires (heavier loads) there are several good options including Sailun.
The endurance is speed rated to 87MPH if one chooses to do so.
Greenhills
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It's amazing how many people think lower pressure leads to uneven wear (tire shops are bad for this).
Our local tire shop did a rotation for me and I asked them to set the pressures at 45/30 (power wagon on 37s) and they told me this would cause uneven wear and it was unsafe and they refused to do it.
Those tires have 60,000 KM at those pressures and around 10,000 at 35/25 (lazy in winter).
I've chalk tested them before and I can run 38/30 without issues, but the 45 takes the vague feeling out of the front end.
Running the right pressure for the right conditions is the best way to go.
Our local tire shop did a rotation for me and I asked them to set the pressures at 45/30 (power wagon on 37s) and they told me this would cause uneven wear and it was unsafe and they refused to do it.
Those tires have 60,000 KM at those pressures and around 10,000 at 35/25 (lazy in winter).
I've chalk tested them before and I can run 38/30 without issues, but the 45 takes the vague feeling out of the front end.
Running the right pressure for the right conditions is the best way to go.
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Yes they didn’t work well for a lot of people. My only issue with them was poor puncture resistance. Every one of my flats was a puncture on forest service roads. I carried 2 spares everywhere.
I haven’t had a flat since switching to LT’s. I’m down to 1 spare and a plug kit for most trips.
Rainier. They came stock on my Haulmark enclosed trailer. Had it a couple of years now, been happy with them. But will get something with a higher speed rating when replacing them.
I had terrible luck with Marathons on several trailers. Bottom of the heap for me. But I had buddies that had great luck with them on similar trailers.
Well, since we turned this into a trailer tire thread, yes, Marathons are cheap garbage made for Walmart. I'm guessing after Walmart saw enough Marathon failures, they didn't re-up the contract with Goodyear so the model was discontinued.
One more vote for Endurance tires. I've pulled many new RV's and the Endurance tire was probably the best tire we ever encountered. Most of the rest are China bombs and many fail before the new RV even arrives at the dealership. I myself even had a 14pr Sailun fail with less than 100 miles on it. Man, those will do a lot of damage when they come apart. I wouldn't hesitate to run them on a flatbed trailer but I'd be a little hesitant to run them on a very expensive camper.
Just put a set (4) of the 4400# rated Gladiators on a flatbed but the jury is still out. They have several hundred miles on them and I've loaded the snot out of them. No failures yet but time will tell. The price isn't bad though and they're heavy as hell.
One more vote for Endurance tires. I've pulled many new RV's and the Endurance tire was probably the best tire we ever encountered. Most of the rest are China bombs and many fail before the new RV even arrives at the dealership. I myself even had a 14pr Sailun fail with less than 100 miles on it. Man, those will do a lot of damage when they come apart. I wouldn't hesitate to run them on a flatbed trailer but I'd be a little hesitant to run them on a very expensive camper.
Just put a set (4) of the 4400# rated Gladiators on a flatbed but the jury is still out. They have several hundred miles on them and I've loaded the snot out of them. No failures yet but time will tell. The price isn't bad though and they're heavy as hell.
I know this, and I’ve done it this way, but that is an excellent explanation you posted here.