How much pressure is dangerous?

Slk

Slk

Joined
Aug 23, 2019
Messages
82
Location
Los Angeles
Bike
2004 ST1300 ABS
I have both tires pumped to Honda recommended 42 psi. I have TPMS installed. When riding on freeway in hot days, some times I see the tire pressure comes up to 50 psi. I’ve been worrying if too much pressure could blow the tires. How much pressure is danger if that could ?
 
Cold pressure is 42 and that's fine... They are constructed to handle normal increases in internal pressure due to friction and ambient temperatures. Worry less, Ride more.
 
The tire manufacturer will always indicate the maximum pressure that a tire is constructed to handle - this can be found on the sidewall of the tire.

The maximum pressure rating assumes International Standard Atmosphere (ISA) conditions, which are +15°C (+59°F) at sea level prevail outside of the tire.

As Joe said, tires are constructed to handle carcass temperature rises and associated internal pressure increases that take place when the vehicle is ridden. As long as you don't exceed the speed rating for the tire (which is also marked on the sidewall), you will be fine. Tires that fit our motorcycles typically have a 'Z' speed rating, which means the tire is capable of a sustained maximum speed of no less than 240 km/h (149 MPH) - well beyond the capabilities of our motorcycles.

So, no need to worry, as long as your tire has no obvious defects (sidewall damage, plugged hole, or it's the same tire that was mounted on the bike in 2004 when it left the factory).

Michael
 
It's the cold tire pressure that is important to pay attention to. Low pressure allows the sidewalls to flex more which builds up heat and it's the heat that damages or destroys the tire. 50 psi hot is not abnormal.
 
Slk said:
I have both tires pumped to Honda recommended 42 psi. I have TPMS installed. When riding on freeway in hot days, some times I see the tire pressure comes up to 50 psi. I’ve been worrying if too much pressure could blow the tires. How much pressure is danger if that could ?
Click to expand...
I have had 57 psi in the rear tire (PR4). Started at 42psi in the morning. Hot day (90+), "spirited" riding in long sweepers. I thought my TPMS was wrong but I checked when I stopped and 2 gauges read the same pressure. The front went up to 50 psi.
 
Last edited:
If you are using a TPMS, check the tire temp, too. I was surprised at how hot the tires got on a hot day (i.e. 90 F +).
 
SMSW said:
If you are using a TPMS, check the tire temp, too. I was surprised at how hot the tires got on a hot day (i.e. 90 F +).
Click to expand...
My system has temps as well. I was a bit surprised at the difference between front and rear. I expected the rear to be hotter but at its hottest (130F when psi was 57), it was some 30 degrees hotter than the front. This may well change with riding style. I was initially worried about the numbers but realized that there was not much a person could do about it. Good example of maybe TMI? The greatest usefulness of a TPMS is the ability to detect a leak before it becomes a bigger problem.
 
It's important to know that the maximum pressure on the sidewalls is maximum cold inflation pressure. The tire manufacturer knows pressure will climb during use. Lowering the pressure from recommended can actually create more heat and lead to higher pressures still. Blowout possibilities are much more of a concern for under inflated tires.
 
Great thanks guys for the reassurance and information. My worries are all gone now. I've been very strict with the tire pressure and make sure both are at 42 psi every time I ride. Cheers!
 
Slk said:
Great thanks guys for the reassurance and information. My worries are all gone now. I've been very strict with the tire pressure and make sure both are at 42 psi every time I ride. Cheers!
Click to expand...
But what if it's a car tire, run flat, on a mountain pass of 10,000 ft, in a storm front, in a left hand sweeper?
 
drrod said:
Good example of maybe TMI? The greatest usefulness of a TPMS is the ability to detect a leak before it becomes a bigger problem.
Click to expand...
^^^ this

before TPMS nobody ever talked about tire temperatures unless they were on a racetrack.

I'll also mention that I've had about a half dozen flat tires over the years and every one of them without a TPMS. There was plenty of advance warning that the tire was going low so I could get over and out of traffic before it finally went completely flat. Tubeless tires are like that, they go flat gradually, not all at once, unless you happen to be really unlucky and run over an axe or something that can create a very large gash in the tread.
 
I've had two freeway flats that by the time I realized there was a problem and was able get to the shoulder and stop, had zero PSI left. Unfortunately the side of the freeway is not a great place to stop. After fitting a TPSM system to my ST1300, I got a warning doing 70 MPH on 405. This time I was able to get off the freeway and find a service station with an air hose and still had 20+ PSI left. This saved me having to pull my compressor out and plug the tire on the side of a rush hour freeway.
 
Last edited:
I agree. Even just 1 minute warning to safely get out of the travel lanes beats having the rear of the bike start twitching at 75 mph in heavy commuter traffic which has happened to me.
 
Tire temps are what to watch, ive seen 55 to 57 psi from desert heat. But 155 mol in temps. You really dont want to see 180 on temps, but the cooler the better. Low pressure lets them sidewalls flex causing heat...so low psi no good.
 
wjbertrand said:
I've had two freeway flats that by the time I realize there was a problem and was able get to the shoulder and stop, had zero PSI left. Unfortunately the side of the freeway is not a great place to stop. After fitting a TPSM system to my ST1300, I got a warning doing 70 MPH on 405. This time I was able to get off the freeway and find a service station with an air hose and still had 20+ PSI left. This saved me having to pull my compressor out and plug the tire on the side of a rush hour freeway.
Click to expand...
good to know that it makes the difference between just getting to the shoulder of the freeway and getting off the freeway altogether, that's a big improvement in warning time.

I guess I have the bar set too low for what I consider acceptably safe outcomes, as one time I locked up the rear wheel on my FZR1000 when my cargo shifted from the seat and I had to ride out the skid until the bike finally stopped. That was doing 70+MPH in rush hour on the 5, riding in lane 3 or 4 of the 7 available lanes. Even though I didn't get off the freeway at all, that was still a good outcome considering the situation.
 
Tires are very very strong in regards to pressure holding capacity. They have to be able to withstand great pressure spikes when hitting sharp edged surfaces even when fully loaded. In the old days when I was at Bonneville salt flats we would inflate tires to 80-100 psi to reduce rolling resistance. I would doubt you could hurt your tire from any over pressurization that was anywhere close to normal. I would worry much more about running under-inflated tires as heat can build up rapidly.
 
When you have to get off an interstate or similar , in an emergency situation - WATCH OUT for deep -cut rumble strips . That's what partially caused my 2015 accident , when my tires got caught in those which deflected the ST sideways as I vectored off into the weeds a different angle .
 
So on my last CT (dark side tire) I saw a finish nail in the middle of the tread. I pulled the wheel off to get it patched and found that the nail was deflected by the steel belts and did not go through. upon closer examination of the tire I found two more older nails that had done the same thing. Had it been a MC tire I would have had three different flats. So I bought a new CT to replace it, aired up to 26 psi. Getting about 40 k miles between rear tire changes...... never going back to those wimpy MC tires.....
 
TourNut said:
When you have to get off an interstate or similar , in an emergency situation - WATCH OUT for deep -cut rumble strips . That's what partially caused my 2015 accident , when my tires got caught in those which deflected the ST sideways as I vectored off into the weeds a different angle .
Click to expand...

We've got these little comb like ridges, oriented perpendicular to direction of travel, at the sides of and between the lanes sometimes. All they do is make a buzzing noise in a car, and they're nearly unnoticeable on a bike. You can feel them but can't really hear them with ear plugs in. They are far too shallow to cause a control problem. the reflective "Botts Dots" are actually more noticeable, especially with zero PSI in your tire. What was Michigan thinking?
 
You must log in or register to reply here.
Top Bottom