tire pressure

The tire sidewall says 40 psi.
The manual for the bike and the stickers all say 25 psi.
What's the right thing to go with?
D8

 

Sidewall but factor for actual load. That is the sidewall will say max XXX#
load @ 40 psi. IME Motorcycles and Honda cars all seem to recommend
ridiculously low pressures on the body stickers, even for OEM tires.

 

The pressure on the sidewall is the absolute maximum pressure that
the tire should ever be inflated to, it is not the recommended tire
operating pressure for your bike. There are a number of places
where you can get the bike and tire manufacturer's recommended
pressures from:

- The bike owner's manual
- A placard on the bike (often times on the chain guard, a frame tube,
or somewhere under the seat or under a side cover)
- The tire manufacturer's website (this is very easy)

25 psi sounds awfully low for a typical motorcycle tire. What year,
make and model is your bike? Recommended bike tire pressures for
my SV650S are 32 psi front and 36 psi rear (per the Pirelli website,
for the Diablo model, they recommend 2.25/2.50 bar front/rear).

 

The bikes are from the early '80s.
I have a GS850G and a bunch of SR250s.
They all recommend pressures less than 30psi but the tires are rated at
nearly 50.
I'll check the manufacturers websitees but I doubt they will go back that
far.

 

The tire lists the maximum the TIRE material is rated for.

The manual lists the pressure the manufacturer has determined to
be the best for traction/handling. Going lower will result in excess
flexing of the tire, weakening it. Going higher will result in a stiffer
tire, with a smaller contact patch on the ground.

While I routinely run car tires about 2PSI higher than the
manufacture spec... Cars have "flat" tread areas, and don't rely on
transitioning to nearly the sidewall for cornering. Slightly higher
pressure on them helps distribute the tread-wear (in my case, the edges
get scuffed off from tight turns, so "bulging" lifts the edges a tad).

Long highway travel may be amenable to a touch higher pressure.
The tires warm up far enough that the extra PSI only maintains the
"firmness" of a colder tire at normal pressure.

--

 

The rating on the sidewall is Maximum allowable presssure.

There`s an old rule of thumb that says :
"If your 'hot` pressure exceeds 'cold` pressure by more than 10% you
need to add air".
Check your pressures fore 7 aft before starting out, then at your
'shakedown` or first fuel stop, (after about 1/2 hr. on the road).
If the difference is more than 10% of cold pressure, you might add a
pound or two.
That said, it's really a judgement call. Does the bike 'feel` right?
Can you tell?
Pragmatist - R75/5 forever!


"Lord, are we worthy of the task that lies before us,
.....or are we just jerking off?"

 

Permit me to contradict you -- often the manufacturer's recs condider
tire life as well as performance characteristics. And loads (riders)
vary.

 

Something in the range of 25-40 psi. Lower will give better ride,
higher will give better handling and fuel mileage typically.


Matt

 

Kaybearjr wrote:

Right. And, with lightweight wheels, tire pressure keeps the rims
from deforming. Bump. Bump. Pssssssssssssssssss.

 

The tire pressures which work best for the Avon AV 45/46 ST tires mounted on
my Ducati ST-4s are 38 pounds in the front and 41 in the rear. I have 4,500
miles on this set with 4 mm of wear showing. They should be good to last
until winter.
Ciao!
Bill