Tires: PSI (manual, fender, or sidewall?)

I've searched- half a dozen forums google style search.
Seems overall it runs 60% say 'what the fender or shop manual says', while 40% say 'run sidewall pressures'.
Fender school says thats what the bike was designed for etc
sidewall crew says modern compounds, tread design etc.
I can find solid logic in both. Tires got modern, but my 30 year old chassis didn't (even with new springs etc, still 30 year old technology)
Whats the current thinking?
I got a set of Dunlop 404's to replace my still good looking but 8 years old Metzners.
With less than 150 miles on them -frankly its maddening, either these tires suck, or I haven't found the sweet spot.

thanks

If Dunlop recommends 30# in new tire X on old bike Z, seems that would be a good pressure to start road testing with.

Dunlop emphasizes that many touring bikes are found being ridden with insufficient air pressure in the rear tire.

Where the tire sidewall says MAX PSI 50#, that means the tire itself is capable of handling up to 50# psi.
But that doesn't mean the ideal normal-running tire pressure is 50#.
The ideal normal-running tire pressure may be 30#.

For example, an automobile tire may say 50# MAX PSI, and the tire information label inside the door says the normal inflation is 30#.

Another example is the FSM Supplement for 1976 KZ900-B1 LTD provides 26 psi front (original Goodyear Eagle G/T ML90-19) and 22 psi rear single rider and 24 psi with two riders (original Goodyear Eagle A/T MT90-16T). Which same pressures are also shown on the oem info label under the seat.
Imo, these pressures are too low for modern tires currently used on the same old bike.

Seat-of-the-pants judgment as to the best ride and feel may be with tire pressures less than recommended by Dunlop, but higher than the oem recommendations.

Within the bounds of safety, it's okay imo when deciding on preferred air pressures to consider butt comfort along with prospective tire mileage.

As the Vetter fairing puts more weight on the front tire, would consider a little more pressure in the front tire than used without the fairing.

Good Fortune!

.

Patton's got it right; the PSI molded into the tire is the maximum pressure the tire can handle; it is not the tire manufacturer's recommended tire pressure. I have always used the pressure recommended by the motorcycle manufacturer (on my bike the label is on the bottom of the seat) and have never experienced a tire pressure related problem. Cranking the tire pressure up to the absolute max will not improve handling as it may reduce the size of the tire's contact patch on the road, plus it makes for a harsh ride. Of course, running under-inflated tires is just as bad. Ed

Agree that sidewall info is related to tire construction. "MAX PSI [COLD]" is your upper limit.

Your owners manual / sticker tells you the MFR's suggestion on where to set it.
This is a starting point for your own tuning.

Medina wrote: I've searched- half a dozen forums google style search.
Seems overall it runs 60% say 'what the fender or shop manual says', while 40% say 'run sidewall pressures'.
Fender school says thats what the bike was designed for etc
sidewall crew says modern compounds, tread design etc.
I can find solid logic in both. Tires got modern, but my 30 year old chassis didn't (even with new springs etc, still 30 year old technology)
Whats the current thinking?
I got a set of Dunlop 404's to replace my still good looking but 8 years old Metzners.
With less than 150 miles on them -frankly its maddening, either these tires suck, or I haven't found the sweet spot.

thanks

Sidewalls are typically MAX pressure, not recommended pressure.

I also ran Dunlop 404. Best pressure depends on rider weight, tire size and a bunch of other things. Start with 30 psi and see if it wear OK.