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Tire Pressure?

Started by RBFD415, November 30, 2004, 02:37:11 PM

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RBFD415

Checking my tire pressure today I noticed they were low (around 20s +). But it occured to me what is the correct pressure? I'm running Dunlop K391 s 120/90 T 18 "Sport Elite" tires say "Max load @ 42 psi cold".

BTW- these tires are old- but not worn- I'm thinking of replacing them anyway. Is this tire still available or is there a better one out there?

Extent

I run Yamaha recomended spec for high speed riding which is 28ft/32rear .  I put Avons on based on reading old threads here, but these are the only tires I'm familiar with.
Rider1>No wonder, the Daytona has very sharp steering and aggressive geometry.  It's a very difficult bike for a new rider.
Rider2>Well it has different geometry now.

Josh M

I run with the same pressures, 28, 32, with Michelin tires.  So far I'm happy with them, but I'm starting to get some cupping on the front.
shiny shiny....

Lou Ras

Seeing that I use "chinese measurements" what would that be in Bar ?? Or something else that we chinese would understand ;) ;)

Lou Ras

Figured it out. 2.2 back and 1.9 front (bar)

silicon_toad2000

I asked a mate the same question once, he had a funny answer so I'll share it here.
He said keep inflating the tyre until you hear a loud bang, then when you inflate the new tyre, dont inflate it quite so much.
But on a more serious note I run 32 lb front and back. I figure when you are braking almost all the weight of the bike is thrown onto the front wheel, i figure a bit more air in there will help stability under braking and also grip.
what do you guys rekon?
One mans clunker is another mans blank canvas.

Extent

I'ld think that higher pressure stiffens the tire but decreases the contact patch (even if only slightly)  I would guess lower pressure (to a point) gives you more grip at the expense of stability.  Too low and it'll wobble all over the place and eat the tire up quicker, there is also a point where running pressure lower no longer increases contact patch and it starts instead to hurt it, but I dont know how much that applies to motorcycle tires.  I know that (car) road racers often lower their tire pressure at the track/strip.  I eagerly await the comments of those more experienced than I however  ;D
Rider1>No wonder, the Daytona has very sharp steering and aggressive geometry.  It's a very difficult bike for a new rider.
Rider2>Well it has different geometry now.

Josh M

I figure the people that design motorcycles and tires have probably gone to a lot more schooling on the topic than I have, so I tend to follow their advice.  Unless I try something and find that it works better...

Car tires and motorcycle tires are subjected to different stresses, so what works for a car won't always work for a bike.  Generally, lower pressure improves traction, while higher pressure will decrease rolling resistance and traction.  On most street bikes this is only about 2-3psi either way from the recommended pressures(I think).  Any more than that, and the tire will wear out quicker and possibly make you end up on your head.
shiny shiny....

jasonm.

I also run about 32 in both tires. Never more. Both have the extra weight of a fairng. Plus I am an animal on the brakes. A few extra psi above 30 in front could save the rim.
looks aren't important, if she lets you play by your rules

silicon_toad2000

good point extent about the contact patch, I'll have a play with my pressures i think. When I got the bike yamahaha put 28 in both (maybe just a difference in calibration of the measuring tool, I havent been calibrated in a while  :) ) I upped them to 32 and the bike just felt amazing, turning into corners was so much easier. JasonM's point about the weight of his fairing probably applies to my case since im a little fatty (110kgs) I figure im a tad heavier than the average joe the tyre pressure is calculated for.
One mans clunker is another mans blank canvas.

Extent

#10
well the 28/32 recomendation is supposed to be good for up to 308Lbs, and then it steps up +4/8 from there for the last weight bracket.  Supposedly bikes are all setup for a 160Lb rider (lucky for me I guess), so most people have quite a bit of suspention work to do to get it "tuned" to them.  I would defenatly experiment with tire pressure and feel what that's like.

One thing I do notice about all of the recomended pressures is they have lower pressure in the front than the rear, I dont' know why, but it might be something you want to try out as well and see how it compares.
Rider1>No wonder, the Daytona has very sharp steering and aggressive geometry.  It's a very difficult bike for a new rider.
Rider2>Well it has different geometry now.