[ST] Recommended tire pressures??

[Neil Lindsey <NeilLindsey@xxxxxxx>]

Recently I purchased a new set of shoes for my Sprint RS (Michelin Pilot
Roads and I think they are excellent).

While having said tires mounted I got into a 'discussion' with my
Triumph dealer/mechanic about the tire pressures that I should be
running.  He maintained that the pressures on the swingarm label were
MAXIMUMS only, and that he would NEVER recommend going with pressures
anywhere near that high, particularly here in the Pacific Northwest
where ambient temperatures tend to be a bit lower.

His contention was that reducing the pressure would provide better grip
at the cost of slightly lower tread life, and that I should be running
the pressures recommended by the tire manufacturer (in this case
Michelin) rather than Triumph.

My contention was that the Triumph recommended tire pressure printed on
the swingarm is based on the expected temperature range in the country
where the bike is sold, and in conjunction with consultation with the
OEM tire manufacturer (in this case most likely Bridgestone).  I also
suggested that if you run tire pressures that are significantly lower
than those recommended by the bike manufacturer, that you run the risk
of catastrophic tire failure and premature wear.  Note that there is no
difference in the numbers specified on the swingarm label for Sprints
imported into Canada vs. the USA, and those numbers are 36 psi for
front, 42 psi for rear.  So that's what I've been running up to now.

When I got home I checked the Michelin website to see what they have to
say and was somewhat surprised with what I found.

The following link takes you to a page whereby you can specify the
country you are in and the bike make/model.  The recommendations include
tire choices, and tire pressures (specified in 'bars', but the
multiplication factor to convert to PSI is 14.5)

http://two-wheels.michelin.com/2w/front/affich.jsp?codeRubrique=2092004103844&lang=EN

Unfortunately the numbers specified for Canada make NO SENSE because, at
3.5 bars and 5.5 bars, these pressures work out to 50.76 psi and 79.77
psi for front and rear respectively.

There are NO pressure recommendations for Pilot Roads for our Sprints in
the USA, which I take to mean that you go with the bike manufacturer's
recommendation.

I also checked UK recommendation and came up with 2.2 bars (31.9 psi)
and 2.5 bars (36.26 psi).
These seem low to me.

Next I compared the Sprint recommendations with those for the Honda VFR
800 V4.  The numbers quoted for Canada were the same as for the Sprint
(i.e.. ridiculous), and there was NO pressure recommendation for VFR's
in the USA.

However the number for the UK were 2.5 bars (36.26 psi) and 2.9 bars
(42.1 psi), which is exactly what Triumph specifies on the swingarm
label.

Hmmmmmmmmmm................

Since the numbers being quoted for the UK seem to make the most sense to
me (notwithstanding the low spec for the Sprint), I checked one more
bike, namely the CBR 1000RR, and came up with 2.5 bars (36 psi) and 2.9
bars (42 psi)

So what do you all make of this??

Neil





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