Air pressure 27.5 X 2.8?
09-25-18, 10:34 PM
#1
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Air pressure 27.5 X 2.8?
New bike, how much air pressure in 27.5 X 2.8 with tubes thanks
09-26-18, 05:58 AM
#2
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Not less than tire manufacturer recommends for the minimum. Are you going to convert to tubeless? That’s one of the main benefits of a using a plus size tire.
09-26-18, 06:29 AM
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The answer depends upon factors including your weight, how much suspension you want the tires to provide, your terrain, what you need to avoid pinch flats, your rim width and how that affects when a low-pressure tire begins to roll over when cornering, stiffness of your tire sidewalls, and even on your willingness to ignore the manufacture-recommended low-pressure number on your tire sidewall. FWIW, I'm 190 lbs and run a set of 26 x 2.35 tires at 15/20 psi front/rear. They might actually be less than 15/20 right now, and that's with tubes!. My recommendation is to experiment, favor lower pressures, and see where you end up feeling the best and most confident when you ride.
09-26-18, 08:56 AM
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can start with reading the sidewall. might have a range like 30-40psi. if so, try the low # on the front & the high # on the rear & see how it feels to you ... right now my 29 x 2.25's feel just right with 25 front 35 rear
09-26-18, 01:25 PM
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09-26-18, 01:59 PM
#6
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Thanks guys. I’m about 180 ready to go with full camelbak. My tires say min 35, rode today with 45 and can’t imagine a better riding bike.
09-26-18, 02:14 PM
#7
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NO NO NO if the minimum on the tire is 35 or some other ridiculously high number ignore it. The only one of those numbers that matters is max and if you are mtn biking there is no reason to ever be near that. The whole point of running + tires is to run them with LOW pressure like in the mid to high teens front and maybe very VERY low 20s rear. You will find must of us running 2.2-2.5 normal tires are running mid 20s front to high 20s rear. With 2.8s at 45psi you are just bouncing off everything like a basket ball.
Last edited by Canker; 09-26-18 at 02:18 PM.
09-26-18, 02:19 PM
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At your weight I can’t imagine running more than 20/25 front/rear, and even that is probably high.
Last edited by Kapusta; 09-26-18 at 02:39 PM.
09-26-18, 02:43 PM
#9
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Wow really that low? You have to consider I came from the days when everyone rode 26” and had rim brakes and there was ONE axle standard.
09-26-18, 04:41 PM
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if you are not going to run the tires that low, there really is not much point to having tires so large. The ability to run really low pressure is pretty much the main point of plus sized tires.
The lower limit of tire pressure for mtb is dictates by one of two things:
1- Pinch flats (or rim strikes if you are running tubeless)
or
2- the tire looses stability in cornering or off camber ground due to the sidewall deflecting too much.
With plus sizes tires, #1 is virtually a non-issue until you go REALLY low. #2 depends on how aggressively you ride, and that is something you just learn by feel.
.
Last edited by Kapusta; 09-26-18 at 05:28 PM.
09-26-18, 05:22 PM
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I'm closer to 200 pounds and run 27.5 x 2.8 tires. I will run 22 to 25 psi for riding on the road. For mountain biking about 15 psi is good, depends on terrian. You can go really low like 10 psi if you like a squishy feel and aren't worried about rim damage. Definitely go tubeless if possible and the bike will roll and feel better.
09-27-18, 07:56 AM
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NO NO NO if the minimum on the tire is 35 or some other ridiculously high number ignore it. The only one of those numbers that matters is max and if you are mtn biking there is no reason to ever be near that. The whole point of running + tires is to run them with LOW pressure like in the mid to high teens front and maybe very VERY low 20s rear. You will find must of us running 2.2-2.5 normal tires are running mid 20s front to high 20s rear. With 2.8s at 45psi you are just bouncing off everything like a basket ball.
At 190 lbs you should be running less than 20lbs. I weigh around 200 geared up on 27.5 x 2.8 Tires. 18psi rear and 15psi front.
Also get those tubes out of there. You'll thank us later.
