Tire Pressure Question

[johnny248]

My '94 Elite came with 3.00-10 42J tires. Manaul states tire pressure should be 18psi Front, 33psi Rear. It looks like the original load rating 42 tires have a max of 331lbs at 36psi.

The replacement tires on there are a 3.00-10 50J max 419lbs at 47psi. The other is a 90/90-10 50J max 419lbs at 36psi.

Now, I work in automotive tire sales. Anytime you change tire sizes, or load ratings, you generally want to use the tire load charts to adjust the psi of the new tire to match the load capacity of the original tire at its recommended psi for the vehicle. The only motorcycle load charts I can find simply show max load at max psi. Nothing that shows the load carrying ability of the tire at different pressures.

Maybe I am overthinking my scooter, but I'd like to know what these tires capacity is at different pressures, not just max pressure.

I could just run them at the recommended pressure of the original tires, or I could just max them out at max psi to make sure the load carrying is there. But if you look at it lime this, the tire that is rated at 419lbs at 47 psi is not going to have the same load capacity as the 419lbs at 36psi if you were running 18psi in both tires. Make sense?

Anyway, does anyone know if such a load chart exists for motorcycle tires? If not, what is everyone running for air pressure with these different size and load rating tires?

[DeanP]

I'd like to know also what Johnny asked:

What is everyone running for air pressure?

I'm running recommended 18psi front, 26psi rear.

[Wheelman-111]

Greetings:

I pump 'em up to the maximum on the sidewall for a couple of reasons:

1. I'm not always good about checking pressure before every ride like I should. But I do give them a hand squeeze to ascertain that there's at least SOME air in them. Assuming the usual, slow rate of leakage, I can go a month before hauling out my pump and gauge. I've gotten pretty good at feeling when it's time.

2. Top speeds will be achieved at maximum pressure and minimum rolling resistance.

I corner a little Geezerly knowing the front tire doesn't have all the traction it should at higher pressures.

[DeanP]

So what is your max tire pressure Wheelman? 32psi?
I'm definitely going to increase mine, but I wanted to see what others are at.

[cruzingratiot]

the front should never be run at max pressure of tire for riding
reasoning
there is not enough weight over the front and on panic braking and fast turns
the front has a greater change of side out on you
( the lower pressure helps the tire have more contact patch )

not saying it cant be done but if the tire is not at operating temp
and the pavement is cold the chance of front tire slide is higher

better to be safe than sorry

[Wheelman-111]

Greetings:

Johnny's question was

what is everyone running for air pressure with these different size and load rating tires?

, so I answered it as what I do, not a recommendation for others.
With the exception of braking, where the scooter's weight shifts almost entirely to the front wheel, I agree completely with everything Cruz wrote. Don't try this at home, kids; I am a trained professional.