Got told to air down to 15 PSI on the Rubicon and thought the guy was nuts

A buddy of mine who's been running trails in the Sierra for 20 years told me to drop my tires to 15 PSI before hitting the Rubicon last summer. I argued with him, said I'd get a bead leak or tear a sidewall on those granite slabs. He just shrugged and said try it or spend the day bouncing off rocks. Well I went down to 18 PSI instead, and after three miles I was bouncing all over, losing traction on the steep stuff. Finally aired down to 15 at the next pullout and holy cow the difference was night and day, crawled right over stuff that had me spinning before. So is 15 PSI really the sweet spot for big granite trails, or was that just the right call for that specific setup on my 35s?

2 comments

2 Comments

alice_hart21h ago

Have you checked your wheel width against your tire size? A lot of people overlook that. I've seen setups where 15 PSI works great on a 8.5 inch wide wheel but on a 7 inch wheel the same tire will bulge too much and give you a totally different feel. The sidewall construction matters too. A stiff 10 ply tire might need a little less air to flex, while a softer load range C tire will get squirrelly faster. So your buddy might be right for his setup, but your actual sweet spot depends on more than just the trail.

the_robert18h ago

Watch how the same thing plays out with something simpler like tire pressure gauges. I've got a cheap stick gauge that reads 32 PSI when my digital one shows 28. Same tire, two totally different numbers. It's the same with cooking - my mom's cast iron skillet holds heat completely different than my nonstick pan, so her 7 minute pancake recipe burns black in my kitchen. You really can't just copy someone else's settings and expect magic.