A question of tyre pressures

[Spelli]

During my first few rides after bringing my old 1100et back to life I have found the handling a bit  “ squirrely “

I just does not feel as directionally stable are I remember on the old fossilised Metzler sports that I have taken off.

The recommended tyre pressure in the manual are 24 front and 28 rear. 

The Mitchelin classic tyres that I have now put on are a much more of a rounded profile than the more mushroom shapers Metzlers. I was wondering if the pressures meet to be changed because of this. 

What pressures do you guys run at ?

[Simbec1863]

I’d be upping the pressures a wee bit modern tyres like a bit more pressure normally.

I’d be running 28 in the front at least it’s a big old lump,even my RGV 250 runs 28/34 on the road 

[Simbec1863]

Quick google gave this 

What pressures should I use on my classic bike? Due to the modern materials used in the construction of these tyres, we normally recommend 25-28 psi front and 28-34 psi rear. What Tyre pressure should I use when riding with pillion/passenger? We would recommend increasing pressures by 1-2psi front and 2-3 psi rear

[Gixer1460]

Blimey!, my first thought was that's low! My daily, of a brand that may not be mentioned, uses 36 / 42psi and has NO sporting pretensions whatsoever, just a regular commuter bike! I can't remember ever INTENTIONALLY running pressures below 30 on anything i've ever had!

[Jonny]

I normaly run 32/32 as a starting point or if I don't have a spec to go from.

[gs7_11]

On modern tyres that are not radials, on a heavy bike like that, I'd be looking at 30 front, 36 rear to start.

If you trawl through some manufacturers sites (Avon are good) they supply pressures to be used on older bikes with modern cross ply or bias belted tyres. You can use these as a guide. They're usually higher than the original tyre's pressures.

Radials tend to be all 36/42.

[Spelli]

Wow thanks guys for the advice.

I looked at the Mitchelin site and it just recommended using the manufacturer recommended tyre pressures.

So glad  to find that there is a reason it doesn’t feel right.

I will check out the Avon site.

[Spelli]

I have increased the Tyre pressures to 

34 front and 39 rear.  Big improvement.

Nowhere  near as twitchy as before.

Thanks very much for  the input all.