Tyre pressure discrepancy

[Seeker]

My riding friend and I disagree on tyre pressure values but I am not confident I'm right.

So here's the scenario: you buy a new bike and the manufacturer recommends "xxx" brand of tyre and fastens a label to your bike telling you the inflation pressures. Let's assume 33/36psi

Meanwhile, some time later you buy a set of tyres that the bike manufacturer hasn't specifically recommended and the tyre manufacturer recommends you run the tyres at 36/42 psi.

Hmm, that's quite a difference. So which is it? Bike or tyre manufacturer?

I have usually followed the bike maker but my friend says to follow the tyre maker and I can see his argument.

[Sir Trev]

To be honest I usually hedge my bets and go somewhere between the two. No scientific basis on that mind you. You've also got the consideration that your pressure gauge may not be that accurate, which is another reason for adding a few more psi than the sticker on the swing says.

Oddly enough, whenever I get my car back from a service they've always inflated the tryes about 10psi over the recommended, per my gauge.

[redtrummy]

Deffo the tyre recommendation for me. Our motorhome runs about 60lb/sq inch but is it that critical? Delivery drivers start with a full load in the morning, empty end of day - do they adjust pressures to suit, do they like heck

[glang]

Yes think tyre manufacturer has got to be the reference but saying that their figure must be for the worst case scenario ie. heaviest bike that tyre would be fitted to and two up with luggage so if your requirements are less demanding you could run them at lower pressures...

[R1ffR4ff]

Tyre pressures are only a recommendation/Starting point. As I let my weight get the better of me I added an extra pound to the front and a couple of pounds to the rear from the WSM 33/36 Lbs. As I'm on a weight loss kick I'll be dropping them to suit. If you see near the end of the life of the tyre uneven inner/outer tyre wear you may know if you have been running too low or too high.



As I do my own Tyre changes I also fitted a 90 Deg Valve which makes putting air in a doddle,




HTH

[Bibio]

This was discussed years ago on the forum. Vant remember their name but the rule of thumb is this. Inflate to recommend manufacturer psi then go for run to get tyres hot. Take reading when hot and for correct pressure its 10%. So if 32 you want roughly 35. If its over the 35 say 37 you add air when tyre is coldcoz the tyres is getting hot if say 34 you take air out. Repeat till you get correct readings.

[Craig380]

For me, Suzi's recommended 33 / 36 works well for grip, feel, good handling and comfort (I'm 75kg / 11.5 stone) with Avon Spirit front, Battlax S23 rear. I've tried higher pressures but it makes the front end feel a bit nervous for my liking.

[mister c]

I've always ran 36/42 on every bike I've owned. I was quite shocked when somebody said what the manufacturers recommend.

The only time that I've ever strayed away from 36/42 was on my track bikes which I ran at 30/30

[NedSVS]

It looks like Avon sticks with the bike manufacturers recommended pressure. I am running of Avon Spirit STs; the front I got well over 9k miles out of, and the rear is nearly worn out at, approaching, 13k miles. I have been running standard pressures on my 2001 SVS, 33psi front 36psi rear, and my only criticism is they are prone to cupping at these pressures, especially the rear. The early sport 600s from Yamaha and Kawasaki that run the same Avon tyre sizes as my SV are all listed by Avon running 36 front and 42 rear; they weigh around 20lbs more than a SV but I probably weigh 20lbs+ more than the average rider. When the new rear, I have already bought, goes on, I will be trying 39psi rear, to see if the cupping situation improves.

[Bibio]

Cupping is more to do with suspension settings and mostly rebound.