OK so no replies… I started messing around with ChatGPT to educate myself on factoring in PSI for load, towing/ off-roading . After prompt engineering for 10 minutes and giving it the data it required it came up with the following…
On all previous road vehicles I have owned, there hasn’t been a need for me to tweak PSI outside of what’s recommended, so this was learning process for me that may help others.
ChatGPT Created this cheat sheet based on the stock tires, with the details of how it arrived at these recommendations further below. (I=ChatGPT)
The on-road recommendations seem straight forward and accurate, I dont have any experience with serious off-roading so when I get some more time will have to verify the accuracy of those.
1. On-Road Tire Pressure Recommendations
How I determined PSI:
• Your tires are LT325/65R18D (Load Range D) with a Load Index of 121 (3,195 lbs per tire at 50 PSI).
• I used standardized LT-metric load/inflation tables (published by T&RA and manufacturers like Michelin, BFG, etc.) to correlate pressure with real-world load capacity.
• Your truck’s curb weight is 6,283 lbs, divided over four tires = ~1,570 lbs per tire when unloaded.
Why the PSI ranges:
Scenario | PSI Range | Why |
| Unloaded Daily | 34 PSI | Matches actual weight; smoother ride without risking underload wear. |
| Moderate Load | 38 PSI | Manufacturer’s doorjamb recommendation; balances performance, safety, and fuel economy. |
| Heavy Load / Towing | 40 / 44–46 PSI | Increases rear capacity for safe towing, per load tables. |
| Max Payload/Trailer | 42–44 / 46–50 PSI | Approaching GVWR; tires need full inflation to hit 3,195 lbs each. |
2. Off-Road Tire Pressure Recommendations
How I determined PSI:
• Based on experience from off-roaders, trail mechanics, and tire physics: lower PSI = more traction via increased surface contact and sidewall flex.
• Each terrain favors different characteristics—some need grip and articulation (rocks), others need flotation (sand).
Why the PSI ranges:
Terrain Type | PSI Range | Why |
| Highway to Trailhead | 34–38 | Normal inflation is safest for paved roads. |
| Packed Dirt | 26–30 | Reduces jarring and improves traction on loose gravel and washboard surfaces. |
| Rock Crawling | 18–22 | Maximizes tire flex for grip on boulders, but risks de-beading without beadlocks. |
| Deep Sand / Dunes | 12–16 | Large contact patch prevents digging in; ultra-low pressure increases flotation. |
| Desert Running | 22–28 | Mix of traction, control, and heat management at speed. |
3. Beadlock Recommendations
How I determined PSI cutoff:
• Based on common off-road best practices and failure cases from tire shops and 4x4 forums:
• Standard wheels rely on air pressure to keep the tire seated on the rim.
• Below 15 PSI, the bead begins to lose its grip—especially when turning or articulating.
• Below 10 PSI, you’re depending on luck and sidewall stiffness unless you have beadlocks.
Why the beadlock cutoff:
PSI | Recommendation |
| >15 PSI |
Beadlocks optional |
12–15 PSI |
Beadlocks recommended for frequent use |
<10 PSI |
Beadlocks strongly recommended |
<8 PSI |
High risk of de-beading without beadlocks |
