re: kz750 ltd h2 1981- modern tires/pressures

hi kzr's

please can anyone advise me of the following:-

my kz was designed and built in 1981.
the old compounds for tires in 1981 was inferior
to modern day tire materials. in the owners
manual it states for a single rider the tire pressures
should be:-

front - 25psi
rear- 22psi

q). are these the recommended pressures
even today?

my friend has a current kawasaki z750 and the weight
is similar to my old gal, yet the tire pressures
are a lot higher.

this is a safety question and worries me that
no one seems to know the answer.

thank you so much for helping me!

regards

angel

I think I run about 30 - 32 front, and about 28 rear.

I can't believe 22 psi is right for a rear tire?

I don't believe the recommended tire pressures were related to tire compounds being "inferior" in 1981. I say this because the recommended tire pressures in 1977 were much higher on my KZ650-C1 than on your newer bike (see tire pressure label below). Does your bike still have the pressure label under the seat? If the owners manual recommends those low pressures (and they really do seem low to me) maybe it's because of the tire sizes or wheel configuration. You might want to send a couple emails to some tire makers to get their opinion on what pressure you should use with their tires. Ed

hi kzr's

thank you for your replies.
my bike is a complete restore, except for the engine.
this a gem of a find 6,600 on a 1981. sadly
no safety labels attached. all powder coated off.

i found the tire pressures from the original owners
manual, page 81.

this is why i'm confused riders!

cheers buddies.

regards.

angel - uk

Just checked the manual on my 1979 KZ750: pressure is 28 psi front, 32 psi rear.

.

My pressures(z500b) front:28psi (dunlop f7)
rear:36-40 (dunlop tt100)
Dry weight 192kg (422 lbs)
At least that's what the factory bible says.

Oh and Martin_csr I think you'll find he's a she.

Current tyres are typically rated with 32 front and 36 PSI rear solo (36/42 for radials) due to more compliant rubber and construction. The higher pressure reduce wear by keeping the tyres cooler. However, the old tyres were generally stiffer in construction and also used less compliant rubber, hence the need for less pressure to ensure sufficient grip and comfort.

Most manufacturers have a fitment guide that also states recommended pressure for any given application.

dear kzr

thank for your reply!

there is a lot of confusion about tire pressures.
so many conficting answers. too high or too low
makes riding dangerous. i will contact bridgestones
the tire manufacturers.

best wishes

Angel UK

Maybe it's imperial pounds?