How low can I safely go with tire pressure?

Equipment
1

so I switched from 35 mm tires to 32mm.

I am finding the ride a bit harsh. for my 35mm tires I was using 50PSI.

for my 32mm I am using 60 PSI.

4 different calculators recommended that. I entered in every detail, measured with calipers, my weight, etc etc (each calculator asked for different things). so pretty confident that is the “right” pressure and I’m wanted to go below recommendations.

how much lower can I go safely? i’m ok sacrificing a little speed…but don’t wanna be flatting or the tire falling off or anything.

i’m running tubless with hooked wheels…riding all on fairly decent roads

at some point I might just switch back to the 35mm…but was wondering if I could try 55 safely? I dunno.

tyty

2

I can’t speak to your specific scenario.

I run 40-45 psi on 28mm tires on mixed road conditions, at 155 pounds.

3

We are all different but I run my 28&32mm tyres (also tubeless & hooked) at 50psi for road riding.

4

The primary risk of lowering the pressure is bottoming the rim out (and pinching the tire). If you aren’t encountering pot holes or sharp edges, you should have some room to go lower. And with tubeless, banging a rim lightly won’t always pinch flat, but it’s not something you want to push the limits on.

5

My total system weight is ~200lbs and I regularly run my 35mm GP5000s tubeless/hooked at 42/39psi. Have not had any pinch flat or rim-strike issues including riding rough gravel. On rocky singletrack with lipped step-ups I rarely get some rim-contact but that’s really out of bounds for purpose.

Silca recommends 59.5/56.5 for New Pavement. I can’t imagine running that much pressure.

I think you can decrease pressure quite a bit.

6

Try the Rene Herse tire pressure calculator. It gives both a firm and a soft pressure recommendation. Even with the soft value you won’t have rim strikes nor roll the tire.

2 Likes
7

You can go all the way down to 0 PSI “safely” with a properly mounted tubeless tyre with the following caveats, otherwise we’d crash every time we got a puncture.

Risk of snakebite punctures and rim impact damage on potholes and other sharp edges, this is a gradual increased, there isn’t a magic safe pressure. Its always a risk if you hit a sharp edge hard and fast enough.

Loss of handling at lower pressures as the tyre stops being able to support itself, you’ll feel the tyre start to roll around when you change direction. Try gradually reducing the pressure until you don’t like the handling. Find somewhere safe to experiment, easy if you live in a quiet street with little traffic, you might have to drive somewhere if you live in a high traffic neighbourhood.

Rolling the tyre off the rim is a risk, but this has nothing do with pressure and is down to out of spec tyres and rims. Unfortunately most manufactures don’t meet the strict tolerances defined by Mavic’s UST so check with your tyre and rim manufacturers if they have a minimum pressure recommendation

8

Entirely depends on conditions, surfaces and weight the bike/rider combo plus the balance of how its distributed.

For me, in general I’ll run 700x28’s at 35-40 psi whether tubed or tubeless depending on which bike and the balance or route ill be riding. Thats with 59kg bodyweight + 8kg bike.

I would keep lowering until you are happy with the comfort & handling. Then you’ll find out how protected from punctures you are as you put on some mileage.

Wouldnt worry about any online calculators or the tyre manufacturers recommended minimum.

2 Likes
9

I run 32 mm tires as low as 50 front and 52 rear.

10

You’ll just have to experiment. Once cornering is affected you’ve gone too low. But there’s usually a fairly wide range that works, and your choice will come down to preference. Rear tyre usually has more pressure as very few bikes are a 50/50 weight distribution across the tyres.

1 Like
11

I know that’s what a lot of people did or do, but if you’re ever going down a steep hill and need to turn, you’re going to want to make sure you have enough tire pressure up front to prevent the tire rolling off or burping. So if you’re already running near the lower limits of tire pressure, use the same pressure front and rear.

Yes, it’s common to run less pressure up front on MTB but that’s an application where the tires are usually much wider than the rim and optimizing for not having rim strikes pretty much takes care of making sure the tire has enough pressure not to roll off the rim.

12

FWIW: I run lower pressures on road, gravel, and MTB than any chart or calculator I’ve seen. I start with their recommendation and then start trying lower until I don’t like it due to tire squirm, rim strikes, etc… Then I go up a few psi or so from there.

2 Likes
13

Then the answer is to run slightly more in the rear.

14

ok thank you everyone…i’ll try to creep it down to see where handling gets funky

fwiw system weight is ~225 lbs and i’m using GP5000 ASTR 32mm tires. had the same brand tires for my 35mm and was running at 50psi and felt like I was on clouds. would be cool to get at least half way. we’ll see what happens.