Tire Pressure - Yamaha FJR Forum : Yamaha FJR Owners Forums
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post #1 of 16 (permalink) Old 04-17-2006, 03:22 PM Thread Starter
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Tire Pressure

I don't know if this belongs here or in "FJR Central," but I rode my '04 two-up for the first time yesterday, so I looked at the manual for recommended tire pressures. I found the OEM recommendation to be 36F and 42R, which is what I have always used solo. Ooops! The OEM recommendation for solo riders weighing less than 198 lbs is 36 front AND rear.
I am interested in knowing what some of the rest of you run solo. Do you recommend sticking with the OEM recommendation?
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post #2 of 16 (permalink) Old 04-17-2006, 04:35 PM
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At my weight, it's very simple: 42 psi in the rear, 24/7.

FYI: the '06 FJR specs 39 psi in the front and 42 in the rear.
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post #3 of 16 (permalink) Old 04-17-2006, 07:03 PM
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I run 38 front 40 rear solo (around 85/90kg with gear), and 40/42 2 up. Sometimes I just run the 2-up pressures all the time.

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post #4 of 16 (permalink) Old 04-18-2006, 06:57 AM
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Ditto with David. Ideally 38/40. But I usually pump up the tyres when I am 2 up or carrying full luggage on a trip and then leave them at that. Works fine for me solo and I am only 85 kilo.
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post #5 of 16 (permalink) Old 04-18-2006, 09:53 AM
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tire pressure

I run 42 in both front and rear because Amain said that's what Warchild told him to do. Ian, Iowa
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post #6 of 16 (permalink) Old 04-19-2006, 01:04 PM
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post #7 of 16 (permalink) Old 04-19-2006, 02:58 PM
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I don't know where you been reading mindtrip, but you need to get your facts straight.

1) Max pressure is exactly that, MAX pressure. Not recommended. Go above, and it might blow.
2) Running max pressure prevends your tires to reach optimal temperature meaning less grip.
3) If you ask tire manufacturers what the recommended tire pressure is for a particular tire on a particular bike, you will get a reply that is typically the same or within a few psi of the bikes recommended pressures
4) racers run nitrogen in their tires not to keep them cooler (that's just the stupidest I have heard in a while), but because the pressure variance between cold and hot is minimal when using nitrogen. This allows them to more accurately set the pressure for the track they are riding on.

You are right in that you should run recommended pressures, but assuming that max allowed pressures are recommended is a stupid mistake and one that in an extreme case could cost you your life. (though granted, on a FJR that chance is unlikely as it is not typically ridden like a sportsbike)
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post #8 of 16 (permalink) Old 04-19-2006, 04:37 PM
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Quote:
Originally Posted by mindtrip
I will admit that running at higher pressures will decrease the tire life; since the tires get hotter they get stickier and wear faster.
Don't want to be picky, but my understanding was that the majority of the heat in a tyre is generated by the sidewall bending as it is loads and unloads with rotation, so if you increase pressure the tyre runs cooler as it flexes less. Any extra wear was down to the smaller contact patch being asked to provide the same amount of grip

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post #9 of 16 (permalink) Old 04-19-2006, 05:07 PM
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My experience (road bikes, and Kart racing):
1 - lower cold tyre pressure generates more heat, due to more sidewall flexing.
2 - lower pressure when cold leads to greater variances over the period of the ride, as the tyre heats up the pressure increases. Cold 34 PSI can increase to 38 to 40 in our environment; cold 42 PSI tends to peak out around 44/45.
3 - Nitrogen in tyres is to control pressure variances, not temps, as it doesn't expand as much as air when heated.
4 - Vehicle manufacturers do often recommend lower tyre pressures that I find to be optimum for me (cars and bikes). They do include the tyre flex as part of their suspension.

Just more thoughts to ponder

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post #10 of 16 (permalink) Old 04-19-2006, 08:22 PM
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Pressure is indicated by bike manufacturer, not tire company.

Nitrogen is used for consistent pressure through varying temperature.

Your tires won't pop if you run 50 psi in them.

Pressure is contact patch and retention of shape.

Some AMA road racers use low 20s on pressure, which shocks me... but they tune it with suspension (and often use nitrogen AFAIK).

I tried, but was unable to prove difference in tire life between running 44 rear, and 36 rear. Theory would dictate, smaller contact patch would wear more slowly... but then you're using a smaller portion of the tire with all of the weight of the bike. Soooo... I just run manufacturer spec.

At the track, I never go as low as the coaches recommend. There I usually run 33 and 33.

Every licenced racer I know uses high 20s at the track. Why don't I? I don't know.

Can't tell you about difference in fuel economy at different pressures... I'm just thrilled that on a bike I get about 3x the fuel mileage of my truck.



- on bikini patrol in FL
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