Tire question

[BrShootr]

Not sure if this is the right section but here it goes:

Bike's manual says 36psi, tire sidewall says max 41psi @ some huge load.

A friend usually pumps up to the reading on the sidewall and another to the manual spec.

I noticed a much more stable ride with it at 41psi, but the AMA website says doing so is bad for tires and it is a common mistake people do when inflating tires.

What do you guys recommend?

[G-Force Junkie]

The number on the sidewall is the tires max rating at the listed weight...this is based on the tires construction and design. When a manufacturer puts that tire on its bike, they often specify a lower pressure due to several factors (load less than maximum weight, desired "feel", etc.) I would tend to go with the bike manual recomendations (assuming you have OEM tires) for general purpose, but typicaly would up the pressure if I was carrying heavy loads (passenger, full panniers, etc.) Often, I think the bike manufactures are letting their lawyers write the manuals...gotta cover their butts. Whatever they recomend has to work with a 120 lb solo rider and a pair of two up , ahem, "Hefty" folks :) This can make their recomendations a safe baseline, but rarely optimum.

[9Dave]

Originally Posted by BrShootr

What do you guys recommend?

Starting with the manufacturer's recommendation and then adjusting a little for load/conditions/riding style.

[swjohnsey]

Neither. If you are looking for optimal handling (track setting) something around 30 psi front and rear. For more tire wear boost the pressure, say 35/40 front/rear. If you want better traction offroad or on dirt and gravel you can reduce pressure to around 20 psi without rimlocks.

[Bigger Al]

Originally Posted by Dave-950

Starting with the manufacturer's recommendation and then adjusting a little for load/conditions/riding style.

Mess around with the pressures and ride the bike each time to see how it affects the handling, braking, etc. It might take a bit of time, but you'll find the right setup. You'll be a better, more confident rider if you feel good on the bike, too.

[GreaseMonkey]

I agree with Al, bikes aren't a one-size-fits-all proposition. I'd suggest you start at 41 psi, ride for a couple days, then drop 1/2 psi and ride it for a few more days. Do this and in a week or two you'll know where it does not feel right for you, so then you have your baselines. Go back up to 41 for a day or two again, then go to half the difference between the 2 numbers and see how that feels. Then you will have an idea if you want to go up or down.

Also, your "favorite" pressure will probably change between summer and winter, so keep that in mind too.

Use a good gauge, and realize the act of checking the tire pressure will sometimes use a noticeable amount of pressure in itself, depending on the gauge used and the tire size.

[ibafran]

you dont say what bike or kind of tire it is. dirt is different from street. etc.

the topic must have been kicked around before now. do a search to see whats been said. take the following with a huge grain of salt:

this is more or less how it was explained to me...regarding street tires.

-use a reliable air gauge. it doesnt have to be particularly accurate. it just has to give the same reading for the same tire psi. use this gauge on the bike every time for consistant readings. all readings should be taken when the tires are cold (ambient air temps). you can take hot readings for the experience. but i wouldnt be changing psi on hot tires unless i knew exactly what i was doing and why. of course, take a reading on a hot tire if you suspect serious low psi. punctures do happen.

-note tire manufacture's max limits. use those as an upper limit for the street. (there are reasons to exceed those limits as an occasional special exception that is not without risk. lets not go there in this thread.)

-start with the bike manufacturer's recommendations. for the thread's example, lets use 35psi for a front tire.

35psi is considered the optimal psi to give a good balance between tire wear / traction / comfort / etc. note that 'comfort' might mean the the bike's suspension works best with this psi. the rider's 'comfort' might very well be a lot further down the list.

if the bike slides easily in the rain (after the road slime has been washed away) then softening the psi by 2-5 psi might improve traction substantially. the tire flexes a little more and gets better grip. yet still has enough psi that potholes and other hazzards are not much more dangerous.

if the bike is heavily laden with a passenger and gear, the tire may squirm enough to not want to hold a line thru a curve. the bike feels mushy like it has a tire that is going flat. the tire may ever judder thru the turn. increasing psi by 2-5 psi may cure the problem.

general results say:
that the lower the psi, the better the traction but the faster the wear.
the higher the psi, wear will be less but traction will be less.
its not a linear feel. a little too much psi and the bike will be skitish and prone to slide. 3-5 psi less than stock and traction may feel terrific. 8 psi might feel 'soft' but managable. 10 psi less than stock may feel aweful. 15 psi less than stock may be optimal for riding the bike out of a sandy ditch to get back to the roadway. but once on the roadway, its either ride slow or air up with a pump.

with experience, you ought to be able to tell , via seat of pants, a 4-5 psi drop from your normal pressures. thus, its worth checking psi with the gauge before the first ride of the day, every day, for the long term experience.

there is a lot to know about tires. this ought to be enough to get you started and build a baseline of knowledge.

let us know how it goes. alternative perspectives are welcome.