What the heck, let's talk tire pressure....

[Festus]

I bought a cheap TPMS for my bike but unfortunately, with my right angle valve stems, the caps would smack the front brake caliper, so I took it off and put it all on Jolene.

I'm bit curious about a few things. On the thing, you could set pressure alarms and temperature alarms. I wondered what temperature the tires run and what temperature would be a good level for the alarm?

On the pressure, when inflated to 40 psi, the pressure while riding is over 46. It made me wonder if all the talk about 40 psi range for tires was right or wrong. I'm guessing that 36 cold is probably 40-42 when riding and 40-42 when riding is probably more like 46-48. I wondered it 36-38 was a better place to be when cold? I've always ran the 40-41 area on my tires.

Seeing how much the pressure rises is making me second guess my decision to run a little higher pressure.

I've also never seen anyone mention the temperatures they set for alarms.

[wheatonFJR]

I don't run TPMs, but I believe people that like mileage want higher tire pressures.

I know I want traction, especially in the cold as I went down in Arky with ambient temps in the mid 30s, so I will ride with lower tar pressures than others. I want traction and good feel with the road. I wear out the back tire first anyways, so I have no issue with fronts with lower pressure causing less mileage on the front that I don't care a lick about.

I get grief for tire tread depth...but that tread depth is never low on the fronts. Not. Ever.

EDIT: BTW, just so no one misinterprets what I am saying. I'm not worried about 46psi operating pressure at all...that's a reasonable pressure increase. It certainly isn't going to damage the tire in any way. I just prefer a lower tire pressure to heat up more quickly and get better grip in the cold.

[raYzerman]

I wouldn't be without TPMS now. Unless the sensors were inside the tire, I'd ignore the temperature. Pressure will vary with ambient temp, so on a hot day, base pressure of 40-41 will turn into maybe 50, on cold days may never get to 44/45. At least from my experience with several TPMS. If freezing out, I'd lower the pressure a couple, but that happens naturally (if you set your pressures at 65F, at 32-35F they'll be down 4 psi anyway).
I'd never use the Yammy 36 psi on the front, handle like a pig, tire wears out faster and unevenly, and what do you think the pressure would be at freezing temp..... budiculous IMHO.

PS, if you had 90 degree stems, you might be able to rotate so the sensors are in the middle of the front wheel.

[wheatonFJR]

I adjust my tire pressures when the temps dip quite a bit on a trip. I wasn't the only one...petey would ask for the tire pump as well on a trip.

[bungie4]

I thought the internet rule of thumb for tire pressure was a rise of 10% from full cold to full hot. So given your example, you might want to increase the pressure to see if you get the range closer (deflating will increase temps)

I'm no expert, but I am on the internet and the pretty close to the same thing. Plus, I know 0Face. Though I won't admit to that publicly.

[HotRodZilla]

The increase in pressure is why the values stamped on the tire are COLD pressure. I run 41 front and 43 rear. I don't think I have ever adjusted down for cold, and I've never had an issue. Still, that may not be a bad idea, but I don't know. What I do know is, the positive difference I've had in the way the bike handles and tires wear is amazing, since I started using the above listed pressures, years ago. I have never worried about temperature. The only way these tires will see temperatures exceeding safety parameters is if you're running near flat at high speeds for a long time.

[ionbeam]

Stuff, in no particular order:

Tire pressure changes at ~ 1 psi for every 10° of temperature change (motorcycle tires are considered light duty 30 - 50 psi tires so the 2% rule applies)

Tire pressure will change with the sun on the tires. Youse guys that change your own tires know the power of the sun.

Properly inflated tires will slowly drift up ~5 psi after ~ 20 minutes riding.

Tires with too little inflation will have temperature go up faster and higher than a properly inflated tire. A large temperature rise is an indication of an under inflated tire.

Inflate your tires to your preferred pressure before riding, riding just 5 minutes first will result in false pressure settings. If possible use the same pressure gauge so you get consistent settings.

Complicated Stuff (Phuck Charles & Boyle and their laws):

Tires filled with nitrogen will have a more stable tire pressure. A compressor with an air dryer will also allow stable tire pressures. Nitrogen is a 'dry' gas. Compressed air will have a lot of moisture entrained unless a dryer/desiccator is used. It is the moisture which contributes to tire pressure variation.

And, here is the space for FJRoss to correct/add to/ridicule my post: Begin:

[bungie4]

I think that Ion guy knows 0Face too.

[Festus]

So the operating PSI you guys are looking for is about 45-48? That seems like a lot.

[wheatonFJR]

So the operating PSI you guys are looking for is about 45-48? That seems like a lot.

It DOES seem that way, only because all the specs reference COLD temp readings...and before tire pressure monitors nobody knew or cared what their tire pressures were during operation.

Tire MFRs are smart and know what the tire pressure ranges will be during operation. They set the COLD tire pressure spec accordingly.

[ionbeam]

Michelin PR 2 GT, PR 4 GT, two up, 42 front, 44 rear stone cold. Typically 12k miles out of the rear tire, the front tire ± 2k miles from the rear. The 'beams plus a week's worth of gear makes a full load Ambient temps don't make much of a difference in tire life, but man, has some road surfaces eaten tires unexpectedly fast. As long as I maintain tire pressure we rarely see more than a 4-5 psi change.

[wheatonFJR]

Believe me Alan, you and Helen are NOT the biggest people to ever mount up on an FJR.

Related to tire pressures (and I will delete this if the OP wishes), I have "heard" from those attending a track day on an FJR, that tire pressures will be lowered. Can you recall what TP you used and what they ended up being, hot?

I presume that lowered tire pressures at track days are used for one of two reasons:
1) heating up more quickly? (and maybe running hotter), or
2) Larger contact patch when cold?

[Festus]

One reason I ask is because I have a family member that has a big camping trailer. He's blown more tires than anyone I've ever met in my life. He's had multiple trailers, boats, etc, and EVERYTHING he's ever owned blows tires. One trip, at least one tire. That's the truth. Before every trip, he makes sure to take any extra wheel/tire or 2 and he ALWAYS blows one out.

I've said for years that he has too much air on them but what do I know? I do know a lot of people have the same stuff he does and they don't seem to have an issue. I've suspected for years and years that once hot, the temperature in that tire, with the load on it, is so great that it's upping his pressure by at least 10, which puts it way over inflated for that load.

I know he's replaced over 50 tires. He's bought cheap shit and expensive shit and it all blows on him. Not leaks, blows.

So seeing the numbers from the TPMS got me curious, that's all.

[wheatonFJR]

Well, tires have two three values, recommended COLD temp pressure, weight rating, and speed rating.

My guess would be that your friend may exceed one of these values.

There are also external factors for your friend:
Driving on pot hole filled roads,
Driving on roads containing steel shards or other construction debris,
Satanic Cult and/or Voodoo colony members constantly cursing his car tires
Buying from Pete's Used Tars to save some money

[ionbeam]

Well, tires have two three values, recommended COLD temp, weight rating, and speed rating.

My guess would be that your friend may exceed one of these values.

There are also external factors for your friend:
Driving on pot hole filled roads,
Driving on roads containing steel shards or other construction debris,
Satanic Cult and/or Voodoo colony members constantly cursing his car tires
Buying from Pete's Used Tars to save some money

Well, tires have two three values, recommended COLD temp, weight rating, and speed rating. And date code. Old tires, old ≠ good.

Do any of the trailers have brakes, either surge or electric? Do the wheels turn freely when jacked up? Boat trailers are hard on bearings if they aren't properly sealed. You probably don't know how the trailers are setup but he is doing something wrong.

We have pulled horse trailers for >100k miles and never had a flat or blow-out. We have a utility trailer and it has never had a flat or blow out but if I don't put new tires on it soon it's going to be risky, they are starting to grow cracks.

[wheatonFJR]

Missed it by THAT much...

[ionbeam]

Missed it by THAT much...

Supplemented, not missed.

[Cav47]

I have run the FOBO pressure monitors and have seen some interesting pressure and heat fluctuations like others have said.

Currently my front tire has a setting at 39. The upper limit is 44 and the lower is 35.
Rear tire is set at 40psi Upper limit is 45.5 and lower is 37.

I arrived at these number limits because I wanted an alarm that lets me know my tires are ready to go. One of the reasons leads back to an "incident" a friend had. He jumped on his bike and headed out to meet me. Well, a few hundred feet out of his drive way, at the first round about, he lost the front tire because it was still cold.

So I set my limits to give me an audible warning/beep to tell me that my tires are up to pressure/temp. If you know how temp and pressure works most of the time, you know that as pressure rises, so does temperature.

I know it is a little bit trivial, but it works for me. I have seen some really high pressures after some spirited runs. Pressures over 50psi were not uncommon. Especially if there was any high speed runs. IIRC some of the temps were approaching 180 degrees.

[kieefjr]

I have run the FOBO pressure monitors and have seen some interesting pressure and heat fluctuations like others have said.

Currently my front tire has a setting at 39. The upper limit is 44 and the lower is 35.
Rear tire is set at 40psi Upper limit is 45.5 and lower is 37.

I arrived at these number limits because I wanted an alarm that lets me know my tires are ready to go. One of the reasons leads back to an "incident" a friend had. He jumped on his bike and headed out to meet me. Well, a few hundred feet out of his drive way, at the first round about, he lost the front tire because it was still cold.

So I set my limits to give me an audible warning/beep to tell me that my tires are up to pressure/temp. If you know how temp and pressure works most of the time, you know that as pressure rises, so does temperature.

I know it is a little bit trivial, but it works for me. I have seen some really high pressures after some spirited runs. Pressures over 50psi were not uncommon. Especially if there was any high speed runs. IIRC some of the temps were approaching 180 degrees.

That pretty much sums up my opinion.

After using tire psi monitors I was really surprised of how much psi rises as the tire heats up and under what conditions and tire brands.

[LKLD]

+1 on the FoBo's.