Author Topic: Tyre Pressures.  (Read 755 times)

Offline Tony Smith

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  • Graduate, Wallace and Gromit School of Engineering
Tyre Pressures.
« on: October 07, 2018, 02:38:12 AM »
Subtitled: "Everything I thought I knew was wrong in respect to modern tyres"


I had new tyres fitted to the GSA on Friday. As they were offering free fitting and balance I decided that I'd let them do the tyres, providing they let me watch.

Turns out that the tyre fitter is the son of the owner and has been fitting tyres to bikes for 25 years because the shop wants them done correctly. Not only did he not have a problem with me watching he invited me into the workshop so he would have someone to talk to while he worked.

As I have been very happy with the Pirelli Scorpion trails fitted to the GSA for the last year going with them again was a no-brainer, best of all the Scorpion 2 tyres they are now selling have a harder compound in the centre of the tyres to stave off the dreaded "squaring off" that prematurely kills tyres that do long highway miles.

I'd noticed some "cuts" on my front tyre and I asked the tyre fitter what he thought might have caused them to which he immediately replied "under inflation". I disputed that and said that I ran 34/36 solo and 35/38 loaded. The tyre man said that 38/42 unladen and 40/46 with a touring load would be closer to the mark (he also convinced me that my tyre gauge under reads by 2 psi by comparing it to his three quality gauges).

At first I thought he was having a lend of me so when i got home I spent time on the Pirelli site - he is absolutely correct.

The pressures I've been running the Pirelli city demons on the R65 were about correct, but the pressures I've put into the Shinkos is too low - I pumped them up to 34/38 but they are still terrible tyres.

What sort of pressures do others run their tyres? I'm interested in modern bike figures, not just R65s.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline tunnelrider

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Re: Tyre Pressures.
« Reply #1 on: October 07, 2018, 03:05:07 AM »
For what it's worth I run my R65 tyres at fairly low pressures, 32 rear/30 front usually.  I had a wee slide in winter after over inflating (for me) the front to 40psi (had no working gauge with me) and lost the front in a shaded wet corner on a cold day in winter, which I thought happened way too easily.  Wasn't braking but coming out of the corner. The tyres were reasonably hard compound (Rinaldi WH21), good in summer, not so good in winter.  But in general I keep to the 32 rear/30 psi for the R65 no matter what tyre I've got on.
« Last Edit: October 07, 2018, 03:34:46 AM by tunnelrider »
'85 Black R65 / '74 GT185 / '83 Pantah 500 / '90 Super Tenere 750  / '01 DRZ400 dirt only

Offline Bob_Roller

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Re: Tyre Pressures.
« Reply #2 on: October 07, 2018, 01:41:55 PM »
I run 40 psi front and rear on the oilhead, Michelin Power Pilot tires .
Also 40 psi front and rear on the Guzzi, 16 inch Pirelli MT 75 tubeless  tires .
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline DonC

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Re: Tyre Pressures.
« Reply #3 on: October 08, 2018, 08:54:55 AM »
Michelin Pilot Actives - 32 psi front, 33.5 psi rear.
From Michelin website, differs from owners manual which calls for 31 psi front, 36 psi rear.

Offline Matt Chapter

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Re: Tyre Pressures.
« Reply #4 on: October 09, 2018, 11:57:11 AM »
I like higher pressures on my monoshock, I try to run 38 front and ~40ish rear (the rim leaks). If I remember correctly I'm running Avon Roadriders.
« Last Edit: October 09, 2018, 11:58:27 AM by mchapter »
'86 R65 with '84 motor ~67000 miles. ?SS lines, Spiegler rotor, Progressive monoshock, Keihan silencers, a piece of Pichler fairing.
'76 CB400F ~26000 miles. ?Weepy SS lines, big dent in the tank.

Offline Barry

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Re: Tyre Pressures.
« Reply #5 on: October 09, 2018, 01:16:49 PM »
Michelin M45's. Solo pressures with 150lb rider 32 psi front and 36 psi rear
Barry Cheshire, England 79 R45