Tire pressure

[Macamon]

I run my forks at 14 lbs, rear shocks on 4 and 2nd from max spring
Me 33 Metzler front with 34 lbs
K491 Dunlop rear with 36 lbs.

This is my old setup on the '79. I still haven't figured out what I will use when I replace the garbage that is on my '80

[Ivan]

then you could look at the rest of his bike and take them off

That and Tod would have the white sidewall all scuffed up in about 4 miles anyway.

[Wildkat]

If I spent nearly $200 on a rear tire, you'd have to put sunglasses on to look at it.

then you could look at the rest of his bike and take them off

[Montreux_Blue]

At least you know you have a spare tire at the house.

[Bigfoot]

Yeah... but nothing worse than a big white-wall on a tire.... except one they don't even bother to wash the blue off of.


Tod

or it having Harley Davidson on the side of it.

[Ivan]

Yeah... but nothing worse than a big white-wall on a tire.... except one they don't even bother to wash the blue off of. If I spent nearly $200 on a rear tire, you'd have to put sunglasses on to look at it.


Tod

Well, to each their own.

I forgot to bring it to 'Hena to get all you guys to sign it. Next time though.

[trbig]

Yeah... but nothing worse than a big white-wall on a tire.... except one they don't even bother to wash the blue off of. If I spent nearly $200 on a rear tire, you'd have to put sunglasses on to look at it.


Tod

[Wildkat]

It never happened........

Where'd you get that photo Jeremy?
Because if you found it on the internet... it's probably been doctored...
lol

[Larrym]

Beautiful Balloons...

Ok... I'll say that I run the max pressure in both front and back tires: 40 Psi. That's what's written on my Kendos. (Yup...the infamous Kendos...)

Why the max? My train of thought is that these are not car tires. Car tires will wear unevenly if overinflated (bald in the middle) and if underinflated they will wear at the edges. The underinflation really shows itself when one looks at a set of tires on the front where they do the job of steering the car. Whatever tires one installs on a car generally they are load rated for the particular vehicle and sized appropriately so that the "contact" patch is the right length and width. In particular the over/under inflation shows up in the width wear pattern because the tire is supposed to have a "flat" profile where it contacts the road. One can do a "read" on these car tires and determine if in fact inflating them to a certain Psi is resulting in a less than optimum "contact" and then adjust the pressure accordingly. Standard operating procedures for the standard car tires which spend most of their life going in a straight line with occasional accelerations/decelerations and low speed curves/turns.

Motorcycle tires are a different animal altogether. The tires are not flat in cross section but rather have a rounded design in order to accommodate the "lean" angle needed to smoothly enter/exit a turn. (I confess that I look at people's rear tire to determine their riding style and I am somehow disappointed when I see the rear tire worn flat like it is installed on a Honda Civic....) Continued straight line/upright and "civilized" riding will wear the middle of the tire bald way before the edges are even touched. This in effect causes the rear tire to act as if it were a "flat profile" car tire and when actually in a sweeping turn or twisty the contact area is both smaller and the transition is more abrupt. (Right at a time when the exact opposite would seem to be needed..)

The ideal bike tire would be solid but with the right amount of compressability and resistance to deformation when exposed to side loading/transverse pressure. But then a solid tire would add a ridiculous amount of weight to the unsprung weight and inertia to the wheels themselves. So we have the shortcut of using tires as "balloons" to deal with the problem of weight/inertia.

The pressure in the tires should ideally keep the tires in the perfect shape in all riding situations: straight and twisty. Reducing the Psi for a more comfortable "softer" ride results in the tendency for the tire to deform earlier/easier when subjected to the side loading of the twisties or a nice sweeper turn. In this "turning" the degree of transverse loading is dependent on the overall weight of the bike and the rider/passenger along with the speed/delta of the turn itself. The sharper the turn/higher the speed the more the tire is subjected to the forces which try to deform it. I would suspect that the G-forces of some of the turns I have been in have resulted in the apparent weight of the bike being far greater than the weight of the bike just sitting in the parking lot. The only thing keeping it from deforming and taking less than an optimum profile/shape is the pressure inside.

I err on the side of putting the max pressure in both tires because I expect them them both to remain in the proper shape no matter what I encounter or have the courage to try/not try. What happens next is just friction co-efficient of the rubber compound/road and the laws of physics.

Haven't adjusted the pressures and done aggressive road tests or measured track times. I also make a dedicated effort to work the bike in order to keep the Kendos from looking like I left my sidecar at home. (No offense intended to any/all sidecar owners.)

[Montreux_Blue]

I don't want to say this actually happened, because some jerk will tell me that reality is subjective. Anyhow, during the next day's ride, it might have just happened that I started loosing tire pressure for what ever reason. Some might say that I was not able to take the corners nearly as fast with a spongy half inflated tire.

It never happened........

[Bigfoot]

Try going back a click on the rear shocks. I run mine on the third setting. Even with hard bags. Drop the pressure in small increments and find that sweet spot. Different tire compounds will make a difference.

I think the point that several of us were trying to make here is that it will be different for each bike and rider - there is not magic number that works for everyone. Tod was not trying to say that everyone needed to run fully hard shocks and max air pressure, just that that is what works for him.

[Ken Talbot]

So I'm thinking drop 3-4 pounds rear tire.Any suggestions?Softer tires?

Terry

Maybe consider inflating with nitrogen

[tw1980]

OK I pumped the tires up from 28 to 40 lbs from 9 to 15 forks and two clicks stiffer on rear shocks then hit the twisters hard today.I felt much better feedback but had to be very careful of rear spinning coming out of corners.I didn't feel comfortable moving my weight back.So I'm thinking drop 3-4 pounds rear tire.Any suggestions?Softer tires?

Terry

[Bigfoot]

Wow, I was gone all day and figured that this thread would be closed by the time I got back to it.

[XJOK2PLAY]

QUOTE: Tod..."I've ripped through 40 and 45 mph curves at over 120 riding with a 1400 Concourse on different occasions with a guy who has quite a bit of track time under his helmet. He leaves me in the straights, but I catch him in the curves. That shouldn't happen.. and can't with a softer setup."


Sorry, Cnuk... gotta go w/ Tod this time on this...

On the Talimena ride, just before I left, I decided to check tire pressures.
Tires are about a year old now, 6000 miles, but still in good shape... E3's front & rear. Read the tire data on the sidewall... max 40 cold, front & rear.
(Mine is a fully dressed bike, I weigh in around 185 # too.)

At this "particular guys' advice" that Tod's speaking about here, I aired them up from 28 to 40. WOW! What a difference! Major handling improvement.
And for the first time since I've had the bike, I clocked gas mileage at 40... up from 32. Handled great in the Arkansas twisties.

For me, at least with ambient air temps around 50 degrees... I like it.
May not in the summer, we'll see.

As for betting that Tod would slide out in the corners... I'll take that bet... (I need the $$$.)

As for Montreaux Blue and how quick his bike is... Trust me guys, he ain't just braggin'! Tod took off in the lead across this straightaway, I followed... looked down, mine said between 110 & 115... Jeremy "blue" by me like I was sittin' still!!! My tail's still draggin' some about that...
BUT... in my XJ's defense... his bike DOES weigh a lot less than mine...plus I got that big 'ole Vetter windshield...
HOWEVER... it sure is nice to tuck in behind in the rain or the cold... so I'll keep it for now, and bow to the faster bike...
Jeremy... that is one killer-fast & cool bobber ya got there... Ride Safe.