Tyre pressures - Any advice

[mhsilverw]

Hi,

Can anyone give advice on tyre pressures on a 1961 AJS 16MS?

I have recently returned to 'classic biking' after realising I can have as much (or more fun) on an older bike, enjoying the ride and surroundings as I could on something more modern...

....and probably a more comfortable riding position (sack-o-spuds) vs cramped knees in armpits that most modern bikes seem to inflict, but don't want to over-inflate the tyres. Whats recommended?

Mark

[GOLDSTAR]

I run mine a little firmer than they should be perhaps, 25/6 at the fromt around 30 at the rear, PSI that is, kind regards

[Eric]

18psi front 22psi rear. Try it Goldstar you will find an enormous difference. These were the original recommendations and are still applicable for Avon Speedmaster front and SM rear. Search forum for a method of working out pressure by weighing front & rear then relating to the data given on the tyre. I wrote it a few years ago.

[griffin]

Not pressure but tyre related.
Read somewhere that the e.u wants to bring in a law stating that all tyres over 4 years old must not be used on the road.Apparently all new tyres have a date code on them.
Well we voted em in !!!

[1608]

Not heard that about Eu directives on the age of tyres for motor vehivles but am aware of the reccomendation that caravan tyres should be changed 5 yearly, I suppose as with most trailers.Many road accidents relating to caravans/trailers are due to poor tyres.I removed my caravan tyres to check and found that the tread had completely disintegrated showing the steel reinforcing, my own shoddy lack of maitenace mind!.
I would think that allowance should be made in the case of bike tyres dependant on the weight of the rider.At 18 st I need at least 28r and 22f on my 18cs.

[Stan Palmer]

That tyre reg sounds a bit ominous. Insurance companies are routinely doing a tyre check for any accident that might have been affected. That would be an excellent one for them to avoid loads of claims. Four years doesn't sound realistic, I have had much older tyres on cars with no degradation due only to age.
Stan

[SPRIDDLER]

I have to replace mine each year - 4,500 to 5,000 miles.
Mind you, now that I've cleaned out my ISA for a second bike (better interest) that should double the tyre life per year (if you see my point).
I've often found stuff in my fridge older than my tyres

[Dick Hobart]

The current RoSPA recommendation is to replace tyres that are 10 years old and not use tyres that have been in storage for more than 6 years. Hopefully anyone framing EU legislation will take due cognizance of that or would that be too sensible!

[Eric]

Had no time this morning due to other commitments but this the posting I made sometime ago. The idea of more weight more pressure is sensible as AMC used to say increase rear pressure when carrying a pillion passenger.

When I first had my bike a 1960 G9 I also had a problem finding out what the recommended tyre pressures should be, as did others in my section at the time. Somewhere awhile later probably in the Jampot I read of a way to determine approximate tyre pressures, you needed access to a weighbridge or large sunken platform scale and it went like this: -

Sit astride the machine and ride the front wheel onto the weighing platform, note down the weight. Repeat the operation for the back wheel, again note down the weight. If you regularly ride with a pillion passenger you may want check the weights again with him/her onboard.

Now look at the side wall of the tyres you should find data that relates to the carrying capacity, for my Avon Speed master 3.25” X 19” front it says something like Maximum Carrying Capacity 465lbs at 36psi, I cant read the back without moving the bike and there are too many things in the way at the moment. From this you could interpolate that for each psi the capacity is 12.92 lbs. At the time I did mine many years ago the result was something like 19 psi front 23 psi rear. When I later found the correct recommended pressures this calculation was very close to those recommended from memory this was 18 psi front 22 psi rear with an added 6 to 8 psi when carrying a pillion passenger.

The same system doesn’t seem to work with modern bikes as my Pan-European has recommended pressures of 36 psi front 42 psi rear and the rear tyre says Maximum Carrying Capacity of 365 kg at 42 psi the Pan is a very heavy bike but its total weight is listed at 287 kg the odd thing is that a Michelin representative said that almost all modern road bikes have pressures of 36 and 42 psi.

I don’t know if you could use bathroom scales the weight maybe beyond the working capacity, if you do try and they go wrong don’t blame me and you will have to purchase SWMBO some new ones.

[Chazzyb]

Modern tyres = modern pressures. Even if it looks like an old-syle tyre. I run my 18S at 26/30 or thereabouts. Or would if it weren't in little pieces. I also have a B*A B25, which is very light compared to an AMC heavyweight. I run that at 24/28. Like wot Eric says, my two modern Trumpets are 36/42!! I'd guess that with modern construction, tubed-type tyres, on an AMC heavyweight bike, the tyre manufacturing might well propose something like 29/33, or similar. Check out what Avon say for their RoadRider tyres for something like a Meriden Bonneville. That's a similar weight to an AMC twin, I'd guess.

Seems Avon recommend 24/29 for Skidmaster/SMII on a Bullet...Edited by - Chazzyb on 17 Mar 2010 8:28:21 PM