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Discussion Starter #1
So I've been noticing as I've been riding more that the tires on my '94 Ninja 250 can feel somewhat skittish once warmed up. Doesn't give me a lot of confidence when leaning.

Not sure if it's just what warm tires feel like, or if I have too much air pressure in them. I fill them up to the amount listed on the sidewall (36 front, 41 rear), but I only weigh 140lbs so should I be riding with a lower or higher pressure? Thanks.
 

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There are two tire pressures listed.

The bike manufacturer recommends one pressure, and the tire manufacturer lists the Maximum cold pressure rating for each tire (on the sidewall). Generally you want to use the manufacturer recommended pressure unless they recommend something higher than is stamped on your sidewall. Have a look in your manual and set your tires like that and see if it feels any different. You might have some other issues too, such as worn bearings or maybe you need a fork brace?

36 seems low for a maximum cold tire pressure. What kind of tire is it?
 

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Tai-Pan
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41 rear on a little bike like that with a light rider is way too high.
I run 41 on a 500 lb zx12 with a 200 lb rider.
I would maybe try 33f 36r but even that may be too high.
I think my wifes r1 suggested is 36f 41r and that seems a bit on the high side.
 

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Discussion Starter #5
Tires are:
F: Dunlop K630F
R: Bridgestone Spitfire 11R
Never even looked before to see if they were the same! The tires themselves are not old at all. Still some nibs on the side of them.

The bike says the tires should be set to 32F and 33R (approximately as the bike lists in kPa). Guess I should start at those numbers and then adjust for weight after.
 

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backslider
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20 year old tires can still have 'nibs' on their sides. But the rubber will be hard, dry, and uncompliant.
 

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Possibly have a bagged suspension. Maybe old fork oil or low. When warms, gets worse. Unfortunately not inexpensive (relatively) to rebuild or easy without tools, stand, etc.

At minimum, change fork oil and flush. Can also revalve and get spring rates specific to weight and objective.

In addition to age, as suggested, tire profile may become squared off from riding without much cornering. That too can cause squirrelly cornering. The other suggestion that it could be worn or poorly adjust head or swingarm bearing should cover all possibilities, other than road surfaces.
 

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Fastronaut
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No one is going to mention mixing two brands/profiles of tires?

Or the fact that that most likely the rear got changed because it was square and the front was left because it "seemed OK" and now the front's cupped?

It really sounds like time for 2 new tires.
 

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(36 front, 41 rear) seems kind of high for a 250 Ninja

On my 2013 650 Ninja, Kawasaki says 36R 32F with a (up to) 200lb load. Manufacturer recommended pressures
should be stamped on the swing arm.
 

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Mmm...beer
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It really sounds like time for 2 new tires.
+1. I've never been a fan of mis-matched tires, for several reasons. IMO, motorcycle tires should be replaced in pairs.
 

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Tire Date of Manufacture stamp:

Note in this example the date is 0304,
which means the third week of 2004



Tire Pressure,
On my bikes:
I weigh about 200 lbs,
Ninja 250r = 30F / 32R
ZX14 = 37F / 37R (for fun riding) 42R (for boring traveling)
 

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Discussion Starter #14
Tire Date of Manufacture stamp:

Note in this example the date is 0304,
which means the third week of 2004



Tire Pressure,
On my bikes:
I weigh about 200 lbs,
Ninja 250r = 30F / 32R
ZX14 = 37F / 37R (for fun riding) 42R (for boring traveling)
Ok thanks for that diagram Shovelhead. Using it, my tire dates are:
F: 30/08
R: 16/09

Dates seem close together, and there is no cupping in the front or rear. I know the previous owner had dirt bikes also so it's a possibility he planned to ride it more but ended up parking it.

Frosty: Thanks for the pressures. I'll set it to that and see how it feels (once this rain stops!) and go from there.
 

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For my 954 the pressure that Honda "recommends" is 36F 42R....which is absolutely ridiculous. I run 31F 33R with Pilot Power 3 tires and it handles great.
 
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