Unpopular opinion: tire deflators are a waste until you hit 40 PSI

I read the spec sheet on my new compressor last month and it said dropping from 35 to 18 PSI only gains you about 2 inches of footprint on a 285 tire. I used to obsess over airing down for every gravel road in Moab, now I just do it for actual rock sections. Has anyone else checked the math on their own rig?

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harper69312d agoMost Upvoted

...and honestly the math only tells half the story on those spec sheets. I ran that same test on my rig a couple years back, same tire size, and the footprint numbers matched what you saw. But what the sheet doesn't show you is how the tire flexes over washboard and loose rock at 15 PSI versus 25. On sharp edges and off camber stuff, that extra sidewall give is what keeps you from getting a pinch flat, not the square inches of contact patch. Plus, for me it's less about the math and more about the ride quality. Dropping to around 20 PSI on a long dirt road saves my back and keeps the cab from rattling apart, even if I'm not gaining much traction-wise. So I get where you're coming from, but I'd say the deflators pay for themselves in comfort and reliability, not just pure grip numbers. Your mileage may vary, especially if you're on heavier tires or a lighter rig.