On Mon, 16 Jan 2017 11:03:04 -0800, Joerg
wrote:

On 2017-01-16 10:43, David Scheidt wrote:
Joerg wrote:

:Yup. Standard bicycle tubes are usually junk. Would you accept it if you
:had to pump up the tires of your car every two weeks? Yet most cyclists
:think this is "normal".

Automotive tires have a much lower ratio of surface area to volume
than bike tires. They're also run a lower pressure, for the most
part.


Truck tires are often operated around 50psi or higher. Like my MTB tires
are.

Have you ever tried to pick up a
truck tire"?

A typical 45" truck tire, say a B.F. Goodrich 445/65R-22.5, weighs,
according to the manufacturer some 215 lbs. Standard operating
pressure is in the neighborhood of 120 psi.

Comparing bicycle tires with tires for other vehicles is, to say the
least, a bit silly.

Unless, of course you plan on a 600 lb. bicycle :-)





... So even if the permiability of the two tires were the same,
car tires would lose pressure slower.


It's the same on motorcycles which have tires similar in shape to what
we ride, just larger.


... Of course, automotive tires are
much more impermiable, because they're heavier and thicker (the
inner liner of a typical car tire weighs as much as a bike tire does,
all by itself.)


Heavier & thicker = better. That why the first line item I look at in
search of a better tire is the weight. Any weight weenie offerings need
not apply.
--
cheers,

John B.