Increasing pressure at temperature. How high is too high?

Paulplex

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Hi all!

So, you should always do your tire pressure when the tires are cool - as warm air expands so a hot tire will be under more pressure than a cool one. I've fitted a TPMS to my bike - cheap one from eBay, but works well enough - and started a ride on a hot and sunny Sunday with 36 PSI in the front, 42 PSI in the rear. An hour or two into the ride, the rear is at 48 PSI ...so I stopped for a bit and let a bit of air out.

Question though ...was that the right thing to do? Should I expect such a high increase in pressure and should I have worried at 48 PSI?

The tires are Avon STORM 3D X-M on front and rear - the front got up to 41 PSI, so they both feel the heat!
 

dduelin

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We don't need to let pressure out of hot tires if the cold pressure was in line with manufacturers recommendations. 48 psi hot from 42 cold is no problem and personally for me is nothing to worry about on the NC700X/NC750X.

Edit to add that ambient temperature, pavement type, rider weight, speed, etc., etc. add significant variation to what highest operating PSI pressures will be seen. Tire manufacturers and vehicle manufacturers take all this info into account to set Maximum Cold PSI on the tire and recommended tire pressures in the owner’s manual and on placards on the vehicle.
 
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Paulplex

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We don't need to let pressure out of hot tires if the cold pressure was in line with manufacturers recommendations. 48 psi hot from 42 cold is no problem and nothing to worry about.
Thanks for the reply; I'll be sure to ensure the tire pressure is right before the next jaunt out ...and may look to tweak my TPMS so it's not bleeping insistantly at 48 PSI too! Is there a point at which you might be a little concerned though..?
 

Griff

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I am curious as to why the TPMS is bleeping at increased pressure. Surely the purpose is to warn one of dropping pressure. At least that is how my car TPMS works ?

Other than that I agree with dduelin's advice. Basically I check the pressure on the morning of a particular day and leave it alone for the rest of the day.
 

dduelin

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Thanks for the reply; I'll be sure to ensure the tire pressure is right before the next jaunt out ...and may look to tweak my TPMS so it's not bleeping insistantly at 48 PSI too! Is there a point at which you might be a little concerned though..?
If the TPMS out of the box has a high pressure warning lower than I may see in normal summer riding then I reset it suit my liking. On the NC I think the Hi P was 48 or I bumped it up to 48. For instance TPMS on the Goldwing was reset to 52 because I see 50+ routinely and don’t want the unnecessary warnings.
 

dduelin

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I am curious as to why the TPMS is bleeping at increased pressure. Surely the purpose is to warn one of dropping pressure. At least that is how my car TPMS works ?

Other than that I agree with dduelin's advice. Basically I check the pressure on the morning of a particular day and leave it alone for the rest of the day.
I think he meant the cold pressure was fine but the TPMS default high pressure warning came at a value that is real too low for the vehicle’s normal use.
 

melensdad

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I am curious as to why the TPMS is bleeping at increased pressure. Surely the purpose is to warn one of dropping pressure. At least that is how my car TPMS works ?
My TPMS has a high pressure warning. It was programmed to go on at 46psi. On my model it is user adjustable so I ended up increasing mine.

When my rear tire was inflated (cold) to 41psi, mine would reach 46pis and set off the monitor. Can't hear it while riding, but come to a stop sign, even inside a full face helmet with music playing, I could hear the warning beep. Mine also has a blinking red light, I noticed that before I noticed the audio cue.

Personally I don't like my Michelin Road 5 inflated up to 41 (cold) because the tire is too hard when it heats up. At least it is for me, especially if gravel is encountered.
 

mrbios

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I agree completely with the posters especially dedulin I only check my tire pressure every few months at the most and usually go by appearance I set the rear a little softer for an increased traction I usually don't run it higher than 32 cold at about 70°. Twice on my scooter at around 70 mph I had a problem with the valves them cracking at the base and the tire going to zero PSI at that speed I felt abnormal handling brought the bike in by leaning gradually to the exit and in fact road slowly on surface streets to a gas station put air and road home that's zero PSI the likelihood that you're going to get down to 15 or 20 and have a problem is very unlikely and I think there are much more serious hazards on the road to pay attention to than worrying about tire pressure. Probably more important is to occasionally inspect the tire all around for a cut or other damage
 

Paulplex

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I agree completely with the posters especially dedulin I only check my tire pressure every few months at the most and usually go by appearance
Hmm - although I recognise that my TPMS is being a bit eager with it's warning for too high a PSI, I'd still personally want to be sure my tires are at a reasonable pressure before I go out ...every few months or so seems a bit reckless to me ;)

...My pre-flight checklist isn't long by any means, but I'll generally check the tires for wear or damage before going out on it, as well as double checking the lights and brakes. Before I fitted the TPMS, I didn't check the pressure every trip - but at least once a week.
 

the Ferret

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I ride every day and checking my pressures everyday would be overkill. I usually check them once a week and find them off a pound or two after 7 days or so.
 

Griff

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My TPMS has a high pressure warning. It was programmed to go on at 46psi. On my model it is user adjustable so I ended up increasing mine.

Personally I don't like my Michelin Road 5 inflated up to 41 (cold) because the tire is too hard when it heats up. At least it is for me, especially if gravel is encountered.

Ok. I learn something every day.

I tend to agree also about 41psi. I only run such a pressure on any of my bikes which specify it, if two up. Rest of the time I run 38 rear.
 

the Ferret

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I'm trying 38 on the rear of mine right now. Solo rider, 165 pounds, no luggage. Can't tell much diff between 38 and 40 so far. Both seem to work fine.
 

DirtFlier

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If you set the rear tire pressure at the correct number when cold, then discover it is way high when hot so release some pressure, it will now be below the correct number when cold! Just leave it alone. :-(
 
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