2 up rear tire pressure

[hoopla]

I put tire pressure monitors on the Rocket after mounting a new rear cobra. Installed 42 psi as usual. Monitor actually showed 41 PSI.
The pressure monitor also monitors tire temperature. The tire pressure had fallen to 39 psi, my own fault, was undoing the monitor as it seemed locked and would only reset by removing for a moment. ( it resets once underway, I learned) The directions of this unit are not so good.
Anyways had noted the temps to be in the high 80's, 86-88 F. Yesterday I put in 44 PSI and during the ride temps were 75-77 F. So about a 10 F change in tire temp.

So I'm wondering what others who ride 2 up use for tire pressure?

My pillion only weighs 125 lb, me 225 lbs.

It seems to me that seeing the lesser temp at the higher pressure would support running a higher tire pressure with a pillion on board as all of that extra weight is applied to the rear tire.

As a comparison the front set at 38 PSI was running much cooler , 58F.

Thanks

Hoopla

 

[mr hunt]

I run 42 rear ... we are 200 and 110 of your yankee pounds and dont carry much luggage ... i leave it there solo unless its track day time where I've run both EMax and Cobra at 36psi

 

[Ishrub]

Your combined 350lbs is my solo!

I use 42 rear and 40 front when touring and yes getting the pressure you want is tricky as the wheels and valve access even with 90* stem bends make it such a pain to get an air hose connected and disconnected without losing air.

Now I over inflate and then loosen the sensor cap without removing it it to release air and recheck monitor. Most of the sensors only reset every minute or so so you have to wait each time before rechecking pressure after adjustment.

 

[1olbull]

I would not exceed 42 lbs.
Look to increasing pre-load on your suspension.

 

[hoopla]

I would not exceed 42 lbs.
Look to increasing pre-load on your suspension.

Thanks, I'm not looking to aid the suspension, seems well set, Hagons, set for the extra weight.

I'm sure some of the added temp is the rear drive assembly, splines and all, adds to the temp the wheel will be at.

I think the added weight and accelleration manifest more friction. I know when I do some hard pulls with my SS,450hp, the rear wheels build pressure as compared to the fronts.

Typically seeing 4-7 lbs build up pressure in the rear and 2-4 in the front, on the rocket.

I will reduce it to 42lbs, as more temp and pressure build as I ride.
Going to do a one up ride just to see what happens, with the pressure.

I will say that the new Avon builds confidence in the turns quite nicely.

Hoopla

 

[Claviger]

Keep in mind your tire temps are what I would call “cold” still, even at 90f.

Tire temps will rise as pressure goes down, wear rate will also rise, and up to a point so will grip. Your allowing the tread blocks to flex more as pressure drops, both giving more contact patch and generating heat while they flex.

Enough pressure to prevent cupping, prevent overheating, and give proper handling characteristics is the right pressure.

For some that number is 36f/40r for others it’s 40f/42r, it depends on how you ride and the total weight of bike plus passengers and luggage.

160f (ish) is generally race track temp. I’d only start worrying about tire temps in the 140f range on the street, you’ll only get that high riding the ever loving Jesus out of the bike. Avon’s don’t really even start hooking up until around 40f, below that, like an iron tire for grip. At ~120f the Avon front really gets sticky.

Your front will always be colder until you start diving into corners, trail braking, and threshold braking at the limit.

 

[1olbull]

Thanks, I'm not looking to aid the suspension, seems well set, Hagons, set for the extra weight.
I'm sure some of the added temp is the rear drive assembly, splines and all, adds to the temp the wheel will be at.
I think the added weight and accelleration manifest more friction. I know when I do some hard pulls with my SS,450hp, the rear wheels build pressure as compared to the fronts.
Typically seeing 4-7 lbs build up pressure in the rear and 2-4 in the front, on the rocket.
I will reduce it to 42lbs, as more temp and pressure build as I ride.
Going to do a one up ride just to see what happens, with the pressure.
I will say that the new Avon builds confidence in the turns quite nicely.
Hoopla

Ya might consider a Fobo TPM set.
I've used it for a few years now and find it very helpful monitoring both tire pressure and temperatures on my motor through my cell phone.