what is the role of varying tire pressures

[mason79]

i'm light and want to optimize, i rode my f with unknowingly, 25lbs fronts on dunlop k291's and 30lbs on the k491 elites in the rear, and they rode great!

when i upped it to 36 and 40 respectivley, they seemed a bit choppy, do i really need high pressures for going under 100 mph's?

any help from anyone with a clue is appreciated!!

[81xsproject]

I like the rubber on the road; the more the better. i too am pretty light @ 150. So, I keep mine just high enough that road imperfection (grooves, seems, crack-fills) don't affect me. When they are too low, I can feel them pull my bike this way and that. Just go with what feels right

[mason79]

Originally posted by 81xsproject
I like the rubber on the road; the more the better. i too am pretty light @ 150. So, I keep mine just high enough that road imperfection (grooves, seems, crack-fills) don't affect me. When they are too low, I can feel them pull my bike this way and that. Just go with what feels right

do you have a "rule of thumb" that you have developed, i.e. minimum, heat and mileage considerations?

btw.... thanks i need this!

[81xsproject]

I wanna say they are both in the mid-upper twenties, but really not sure. I am sure that one of the guru's will chime in and slap my ignorant OPINION in the back of its stupid head Were you feeling the road pulling the bike around at the lower pressures? My tires seem to be wearing okay for Kenda Crappo's. It is tough being a little-guy around THIS croud

[mason79]

with my lousy riding i feel the road pulling me all the time regardless, your opinion matters to me, i'm 5' 7" 136lbs, and i guess i gained a pound over the weekend


hmmm.. mid to high twenties, both the same?

and thanks for the feedback it really helps!!

[skids]

Oh no...you just lost all credibility! ;-)

Originally posted by 81xsproject
My tires seem to be wearing okay for Kenda Crappo's.

[Just In Case]

Hi. My XS1100E Yamaha Manual says:


[CODE] Front Rear
Upto 90kg 26 28
90kg to 153kg 28 36
153kg to 217kg 28 40
High Speed 36 40

So for us lighter guys, we can get away with a lot less pressure in the rear. No idea how fast high speed is though.
David

[Just In Case]

Sorry about the mess in my coding, I tried to edit it but my editing time expired before I got everything looking pretty

[randy]

I don't know, I just read the info stamped on the tire and go with that. Remember, the specs for our bikes were written 25-30 yrs ago, when tires were nothing like they are today.

I say go with the tire mfg's recommendations.

[Just In Case]

Originally posted by randy
I don't know, I just read the info stamped on the tire and go with that. Remember, the specs for our bikes were written 25-30 yrs ago, when tires were nothing like they are today.

I say go with the tire mfg's recommendations.

Good point, though I've only ever seen max load/ pressure info on the side walls, so you might want to check the manufacturers website. But you'd need to know the weight on each axle to make a safe choice. Perhaps put the bathroom scales under each wheel while sitting on the bike (if you're allowed to, of course) Actually the scales might not go high enough for the XS???? Hmmm, time to think up a lever/ spring scale setup

[GNEPIG]

.. i dont know if this is the same or not, but i base my tire pressures off of the specs of a new model bike that i service/repair where i work. one that uses the same tire sizes and weighs about the same as our bikes. i even use the same tires as one of these models
the 130/90/16 rear set at 36 psi
the 100/90/19 front set at 32 psi
i have gone up and down with these pressures on my bike, but noticed that these numbers seem to give me the best feel for the road on my 79 Special
.. hope this helps

[prometheus578]

"I'm getting "tired" of this"

Does one set the pressure low as the bike maker wants so that you get a comfy ride and like your bike, or to the tire makers pressure so that they'll last longer? Yes, there are a lot of other variables, such as speed, load, type of bike, and how one plans to ride.
Worked at one shop where the rule was: rear tire: 4 lbs less than maximum, front tire 10% less than that.
Current shop says: 36lbs rear, 34lbs front. (race bikes 34 and 32) depends how much grip they want, not being overly concerned with wear characteristics.
Big bikes, with big riders and bigger wives, I alway max out the rear, and do a few less than max on the front.
If an individual is sensitive enough to feel the difference, then he can damned well set them to anything he likes.
Just In Case writes:

High Speed 36 40

rounder tire, less rolling resistance and less flexing, hence less heat build up. I would consider this for fast, highway cruisin', but would drop it down if planning on whippin' around curves and such, then wanting a little more flexing and a larger tire contact patch on the pavement.
Can't have it both ways.
I think anything in the 20's is too low.
I run 34 and 36 and am content.

[81xsproject]

See, I told you they'd get on here and slap me around

[xs650mike]

I'm light (suited up 150 lbs.) but I like my tires on the hard side for more precise steering. Kenda cheapos? Tried Kenda tires twice, both were out of round. The only cheapos I really like are CS Barracudas.

Different tire brands and models like different pressures. I just got a free barely used Avon Venom X rear because my friend found the handling "evil" on his Harley. He was running Harley's recommended pressure which is for the OEM Dunlop. The Avon requires more pressure according to the manufacturer. I'm currently running 30 lbs front (Barracuda H) and 36 rear (Venom X). Traction is there. Did a lot of riding in the rain this winter with nary a slip. On dry pavement the bike will heel over until hard parts scrape with no problem. This combination of tires works well, a lot better than the Metzler ME33 front and Dunlop Elite II that I had before.

[mason79]

Re: "I'm getting "tired" of this"

Originally posted by prometheus578
Does one set the pressure low as the bike maker wants so that you get a comfy ride and like your bike, or to the tire makers pressure so that they'll last longer? Yes, there are a lot of other variables, such as speed, load, type of bike, and how one plans to ride.
Worked at one shop where the rule was: rear tire: 4 lbs less than maximum, front tire 10% less than that.
Current shop says: 36lbs rear, 34lbs front. (race bikes 34 and 32) depends how much grip they want, not being overly concerned with wear characteristics.
Big bikes, with big riders and bigger wives, I alway max out the rear, and do a few less than max on the front.
If an individual is sensitive enough to feel the difference, then he can damned well set them to anything he likes.
Just In Case writes: rounder tire, less rolling resistance and less flexing, hence less heat build up. I would consider this for fast, highway cruisin', but would drop it down if planning on whippin' around curves and such, then wanting a little more flexing and a larger tire contact patch on the pavement.
Can't have it both ways.
I think anything in the 20's is too low.
I run 34 and 36 and am content.

you see, and i almost was going with seat of the pants... thanks

On dry pavement the bike will heel over until hard parts scrape with no problem

hey xs650mike,

i don't know if i'm going to push the bike to a point of scraping(scaring myself without that) but what parts do hit when it does?