I am not going to try to figure this out, is one slightly above and one slightly below the 15 percent?
When they first came out with the 15 percent, I thought that was absurdly too low for front, they did not clarify that initially that the front should have more than the 15 percent for braking reasons. I think it was originally published in Bike Quarterly, I have a one page version with no date. The ACA version has a date of 2009, I think this came out later.
https://www.adventurecycling.org/default/assets/resources/200903_PSIRX_Heine.pdfBecause I thought it too low, I generally run my front at about 70 to 75 percent of the rear pressure (if rear is at 80 psi, I would run front at about 60 psi). I have no basis for this ratio that I have been using, but have been doing it for years and it has worked well. But I have run my front lower than that on rough chip seal when the front gave me too much vibration on the rough pavement.
Right now on my Lynskey with 37mm tires, I have an old Marathon XR on the front, I run that a bit higher than my 70 or 75 percent of rear norm because that is a high rolling resistance tire and at lower pressures it feels like I am pulling a boat anchor.
For touring, I think I usually have my rear about 15 percent tire drop, but with a heavy load that 15 percent might be the tire max pressure or close to it.
Years ago, I basically took their chart and ran the lines farther to the right with a straight edge because with my touring load on the rear tire, I was off their chart. My 700c touring was on 37mm tires. I also used the 37mm pressure for my 40mm Marathon (with Green Guard) tires on my 26 inch wheel Sherpa.
I will probably never run tubeless, but I have heard that road (narrow) tires that are tubeless at low pressure can "burp" in corners and suddenly lose enough pressure to cause crash and injury. I have no clue if these pressures they are talking are low enough to be a hazard for tubeless or not, just commenting on that. If there is a minimum tire pressure listed for a tubeless tire, I would NOT go below that.
Interesting article.
Thanks Dan.
Schwalbe Marathon Plus HS440 Tyre with Reflex - 26 x 1 3/8 Inch / 650 x 35A 37-590
ETRO37-590
Am I right in thinking the tire width is 37mm?
Best
Matt
I would say that is close enough. Or see what they say in the link I posted above.