yannisg

I have DT Swiss XR 361 Asym 29 rims on my gravel bike with Pirelli Cinturato Gravel H – 700 x 40c tubeless tires.

Twice the rear tire has "blown off" the rim (inflated at 70 psi)
Max pressure 73 psi. Rider wt 80 kg
Bike is 2 years old, and tires have 300 klm on them and no sign of wear.
LBS mentioned that the max pressure refers to using a tube in the tubeless tire which doesn't make sense to me.
Could it be that these tires are not compatible with the specific rims.
There have been cases of blow-out tubeless tires being incompatible with certain rims.
Any recommendation appreciated.

Ryan_M

That pressure seems excessive! I use that pressure on my 700x28 tubeless tires and I'm 86kg. Even on my tubed hybrid 700x42 I use 45psi and could probably go a bit lower.

Eric F 

Your pressure is way higher than you need. I weigh a bit under 83kg, and ran about 38-40psi when I was using the 40mm Pirelli Gravel H. I'm using 35mm Pirellis on my gravel bike now, and run 40-45psi, depending on my route.

Andrew R Stewart 

Independent of any tire pressure opinions there's the fact that not all tires (as labeled as tubeless compatible) and not all rims (equally TL compatible) are made to the same fitting dimension. Manufacturing tolerances exist for both. Rims tend to drift more from the "perfect" spec as they are made batches and any one batch can drift from the next or the previous. The tires are made in a mold that doesn't tend to see as quick a wear or tolerance drift issue. But if that mold is only a bit off many thousands of tires will be so too.

Then there's the parallel aspect of the loss of a hooked edge to the rim's inside driven by the need to lower the cost of carbon rim manufacturing. The loss of that hooked edge means there's less mechanical interlocking and locating between the rim and tire. Andy

tyrion

It's not uncommon for a tire to be spec'd for a lower max pressure when run tubeless (although it would make sense for them to put those specs on tire itself).

As others have mentioned, 70psi seems way to high. I recommend you use a tire pressure calculator. I like the Silca tire pressure calculator.

https://silca.cc/pages/sppc-form

yannisg

Thanks for responding. It seems the tire pressure I am using is too high.
From the tire pressure calculator 40 psi seems adequate.

Eric F 

Try 40pi and see what you think. Adjust up or down from there, depending on whether you want it firmer or softer. I was really impressed with how efficiently the 40mm Pirelli H rolls at 40psi, while still handling rough terrain very nicely.

vespasianus

The only thing I will say is that once a tire blows off a rim, it will either do it again or worse. Don't use it tubeless.

For most tubeless tires, I find that going over 50 PSI is bad.

shelbyfv

I stupidly over inflated and blew a tubeless tire off the rim. Though not visible, apparently a section of the bead was damaged and thereafter would not stay on the rim. Had to scrap the tire. I didn't think to try it with a tube. I agree 40ish sounds more appropriate.

sean.hwy

On the GFs Liv gravel bike I replaced the heavy factory off road tire 40mm with a 32mm gravel king slick. Since it looked like a road tire I filled to max psi to ride more like a road bike tire. I don't think the wider factory giant wheel and smaller higher psi gravel king slick got along well. The 90lb GF on like a 3rd ride blew out the front tire. After that always ran at least 10 psi under max on the factory Liv wheel. Had zero issues with the same tire on the lightbicycle carbon wheels meant for high psi road tires.