Tyre pressure PSI etc

Bigtallfatbloke

New Member
I have some schwalbe marathons and a new road pump which I am itching to use...however I cannot see on my tyres what maximum pressure they will take as the text is so small I cant read the bloody thing....any idea what a good pressure would be for such tyres? My pump says it will go up to 120psi, is that going to be to much? I have only ever pumped up with a hand pump until the tyre felt hard enough.
 
Pump up the volume BTfB - I weigh 105kg (+/- :blush: ) and the tyres feel good at '120psi' or thereabouts. If it's raining then the pressure comes down a bit... by feel really. No idea if my Tesco track pump is accurate, but it works.
 

Hurricane Steve

New Member
Location
Hamburg
Hi bigtalfatbloke
Tyre pressure is important, I'd suggest using the tables Punkypossum posted. You not only have a better ride, but if your tyre is under pressure you have more friction which means wear and tear and its a tad more energy needed from your side, the rim tape protects the tube from the spokes and any sharp edges, and if the tyre is under inflated this tape could shift from position and the result being a pucture. I suggest inflating to 10psi or so under suggested max. Give it a try and you'll see in no end what a difference the correct pressure makes.
 
Ignore what's written on the side of the tyre, it's not meaningful

See what His Holiness Sheldon says
http://www.sheldonbrown.com/tires.html#pressure

Most tires have a "maximum" pressure, or a recommended pressure range marked on the side of the tire. These pressure ratings are established by the tire manufacturers after consultation with the legal and marketing departments.

The legal department wants the number kept conservatively low, in case the tire gets mounted on a defective or otherwise loose fitting rim. They commonly shoot for half of the real blow-off pressure.
The marketing department wants the number high, because many tire purchasers make the (unreliable) assumption that the higher the pressure rating, the better the quality of the tire.
Newbies often take these arbitrary ratings as if they had some scientific basis. While you'll rarely get in trouble with this approach, you will usually not be getting the best possible performance with this rote approach.
Savvy cyclists experiment with different pressures, and often even vary the pressure for different surface conditions.
Optimal pressure for any given tire will depend on the load it is being asked to support. Thus, a heavier rider needs a higher pressure than a lighter rider, for identical tires.
Since most bicycles have substantially more weight on the rear wheel than on the front, the rear tire should almost always be inflated to a higher pressure than the front, typically by about 10%.
Rough surfaces generally call for a reduction in pressure to improve ride comfort and traction, but there is a risk of pinch flats if you go too far. Rider skill also enters into this: more experienced cyclists learn to "get light" for a fraction of a second while going over rough patches; newbies tend to sit harder on the saddle, increasing the risk of pinch flats.
He does detail the problems of over- and underinflation and also has a table suggesting pressure baed on tyre sized and your weight.
 

Danny

Legendary Member
Location
York
As I am not convinced you can trust the pressure gauge on a pump, I usually just rely on pressing the tyres to see if they feel hard enough.

Or am I just being a luddite?
 

Tynan

Veteran
Location
e4
My marathons are marked for 100psi, what Sheldon says natch

I go 100 front and 'a bit more' on the rear, the harder the better is my experience, unless your fillings start coming loose
 
OP
Bigtallfatbloke

Bigtallfatbloke

New Member
many thanks all.

I pumped up front and rear today to 100psi and all seemed well enough on todays loop....Tomorrow I will let just a touch out of the front tyre as per the Sheldon article and see how I get on. I reckon I have been riding with my tyres to soft a stoday the bike seemed quicker and lighter, although I did slip a couple of times on cornering which i have never done before.
 
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