Tire pressure concern

[drrod]

I have seen rear tire pressures well over 50 after starting out at 42 cold. I thought the TPMS w as wonky but stopped and checked with different tire gauges and they all read pretty much the same. Nothing I can do about it, so I pretty much ignore it.

 

[Larry Fine]

Sounds like it's doing what it's designed to do. Heat raises pressure, stiffens tire, and reduces more flexing.

 

[red one]

I do what the owners manual says. Set mine at the recommended pressures cold. Works on both my cars and motorcycle.

 

[Mellow]

Is that a consensus among all the Toms or just you?

That's a lot of Toms....

 

[Gerhard]

When I bought my RT 10 years ago there was a lot of discussion about the discrepancy between dash displayed pressure and the riders favourite gauge. The BMW tire pressure sensor corrects pressure to a standard temperature (it might be 20°C but forget the actual temperature) There were riders back then that tried to outsmart the system without reading the manual which stated that the reading was corrected not actual. It is kind of the same when buying gas gasoline in Canada, (every pump has a sticker that indicates it is temperature corrected volume) you don’t actually buy a litre at any temperature but actually a corrected volume.

 

[Al st1100]

I would say 100 psi is too much the manufacturer doesn't give a "too much tire pressure hot" so they don't give a rats ass what that would be and either should you.

 

[ST Gui]

I use 42lbs cold because that's what Honda recommends. I have no idea if a Keith Code graduate would find it correct for their type of riding and their weight on my ST. It seems fine to me as in close enough for gubmint work. AND it makes it easier to get on the center stand. That and 42 is the universal answer to everything.

Now that I have a TPMS I check the tire pressure before every ride and make sure it's at 42. That's the last time I check it until the next morning of the next ride or an alert from the TPMS. For years there was no TPMS for me and I rarely checked the pressure unless the tire looked low or handling felt mush. At that time the pressure was usually really low. So I don't sweat it now.

 

[skidgillen]

Ran 162 miles today with 42 cold temp PSI before I left, and 49 PSI when I got home.

 

[Al st1100]

BMW air is much better for tires even when on a Honda with a low quality gauge…

is that where BMW Airheads started?

 

[wjbertrand]

Don't forget summer air is warmer & warm air is less dense, so you need to put more in to get the same pressure as winter air.......

There was a craze some time ago about filling tyres with Nitrogen.
Anyone know if this was a thing for bikes or just cars?

It's still a thing for super critical tire pressure control, such as for racing where thousandths of a second on a lap time can make a difference. For street vehicles it's mostly a gimmick. The primary advantage of nitrogen is that it's the cheapest way to get an almost totally dry gas. Moisture can cause exaggerated pressure changes with temperature as it's always changing state (liquid -> gas -> liquid again) at ambient temperatures. The same number of molecules of water occupy way more space as a vapor (i.e. contributing to pressure) than as a liquid. Water can get inside of tires from ambient air delivered buy a compressor, though it's usually not enough to be a problem. Poorly maintained compressors though can accumulate enough water that when you attempt to use the air hose it blows out a spray of water and air! I once had enough water inside a tire (wife's minivan) that it made the tire impossible to balance. The car would vibrate like hell at highway speeds even after several attempts to rebalance it. Finally one clever tech broke the bead and found several ounces of water inside. He poured that out, dried the inside of the tire with a heat gun and finally solved the vibration issue. This experience is why I don't believe in movable media inside a tire is viable way to balance one.

Regarding temperature rise, the highest I've seen is 50 - 52 PSI, interestingly both on my ST1300 and current Super Tenere. One interesting bit is that I've noticed different brands of tires run hotter or cooler. Running Michelins or Bridgestones on my Yamaha, temperature rises are similar, but when I fitted Shinko 705s, temperature rise was faster and reached higher levels than with the other tires. I've only seen pressures beyond 50 PSI with the Shinkos. Gas mileage was a bit less with them too. Thinking those tires just have more rolling resistance/friction and therefore create more heat.