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Tire Pressure Observation

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Sharky1948

Junior Member
I've installed the remote tire pressure monitors on my '09 FLHR. (I don't want to take any grief about the value. I also have the digital oil temp/dipstick and I check oil pressure, oil temp, tire pressure before and after every ride. It just makes it easy!!)

Anyway, back to my observation. I inflate the tires to 36psi F and 40psi R per the specifications. At the beginning of a ride today the temperature on each tire read 65F. After a long ride, the front tire reads 37.5 psi and 70F, a 1.5psi increase. The rear tire reads 47 psi and 90F, a 7 psi increase due to the greatly increased temperature, presumably because of proximity to the exhaust.

Obviously the relative difference in pressure between front and rear is not constant over the course of a ride.
 
Just a 5 degree increase in temperature on your front tire from cold to long drive Hot.? That sure is not much.

I have something to add that may be of interest to you. A few months back there was a thread about running nitrogen in tires. Some said it was good, some said it was bad. Some said it was a waste of money and some said they even used different gases. Well anyway I had to see for myself. I already had a cylinder of 99.999% nitrogen so all I had to do was hook up a regulator. To run a good control test, I tested pressure swings from cold to hot using ordinary air. My swing was 6 PSI in my rear tire & 4 PSI in my front.
I Completely (and I mean completely) purged the air from both tires to nitrogen ( 3 times) and here are my readings. I was a little disappointed. I now have a 1.5 PSI swing on the front tire (from the 4 PSI). And a 2 PSI swing from 6 PSI on my rear. I don't know why but I was really expecting better results than that.
I am still testing to see if the tires loose nitrogen (pressure) over time. The claim is less lose over time with nitrogen. My wheels are factory billet/ non-laced. We shall see.
 
Hoop nitrogen is suppose to give a better ride and cause less degragation of the inside of the tires
 
Considering the air we breathe is 78% nitrogen anyway and 21% oxygen, I think it's a bit of overkill myself JMO. I'm sure there are many that will endorse it's use in any event.
You can top off a tire with regular compressed air when running the nitrogen.
More often than not the tire will be worn out before the cost and benefit of the nitrogen use in the tire will be realized.

Here's what's advertised about it by a nitrogen equipment manufacturing company.
  • Longer tire life:
    By maintaining proper inflation pressure and minimizing tire aging, tire life improves by up to 25%
  • Eliminate chemical aging of the tire:
    As oxygen and water vapor permeate through the side wall, the rubber degrades, causing the tire to deteriorate. Nitrogen is inert, halts the chemical aging of the tire, and prolongs tire quality
  • Nitrogen is very dry (-50°F dewpoint):
    Nitrogen eliminates condensation and rim corrosion, and will allow tires to run cooler and provide a safer ride
  • Maximize safety:
    Cooler rolling temperatures minimize autoignition and catastrophic blowouts, providing a safer ride.
Nitrogenchart.gif

bills985

bills985
 
Sharky1948 said:
The rear tire reads 47 psi and 90F, a 7 psi increase due to the greatly increased temperature, presumably because of proximity to the exhaust.

I doubt the proximity to the exhaust makes more than a tiny difference. The temp. difference is due to the friction of the rear tire pushing against the pavement to keep the mass of the bike moving. Front tire is just getting pushed. A few years ago I was watching the Daytona 200 motorcycle race on tv. These bikes have all kinds of 'puter telemetry on them. One of the factory techs claimed that due to wind resistance and other forces, the rear tire was turning 7 mph faster than the front tire on the back stretch at 180+ mph.
Click to expand...
 
Increased temp in the tyre pressure is usually caused by heat generated by the sidewall of the tyre flexing
this situation would tend to indicate that there is insufficient pressure in the rear tyre
the difference between a hot and a cold tyre should be around 4 psi
so increase the rear pressure by 1 or 2 psi and try again
be aware that tyre pressure is affected by atmospheric conditions so should be checked and adjusted daily for optimum performance

Brian
 
fin_676 said:
Increased temp in the tyre pressure is usually caused by heat generated by the sidewall of the tyre flexing
this situation would tend to indicate that there is insufficient pressure in the rear tyre
the difference between a hot and a cold tyre should be around 4 psi
so increase the rear pressure by 1 or 2 psi and try again
be aware that tyre pressure is affected by atmospheric conditions so should be checked and adjusted daily for optimum performance

Brian
Click to expand...

Good point on the sidewall flexing. I was running 40psi with only me at 190lbs on the bike. By the book, that should be more than enough. But, I'll try another couple of psi and see what happens.

I wonder if it's possible that the sidewall is breaking down. I've got 12000 miles on my tires, just over a year old. Plenty of tread left. Plan to replace them over the winter.

I do check before/after each ride so it will be fun to dial it in.
 
Jack Klarich said:
Hoop nitrogen is suppose to give a better ride and cause less degragation of the inside of the tires
Click to expand...

Yes, I have read that also. The ride seemed the same to me. It was really
hard to tell. I did not feel any "big" change. But I do like the fact of having a dry condition inside the tires. Most air compressors will blow a Ton of moisture along with the air. I have de-mounted car tires and could not believe the corrosion on the inside mag and bead area caused by moisture in the tire. That in itself may be worth something. But only time will tell since this is the 1st time I am trying it.

Hoop!
 
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