4

So, I've very recently bought a brand new "Radius Targa"... The pressure I'm told to inflate my tires to (which it says on the side of the wheel) is 50 PSI, the only measurements I can find on the wheel to tell me anything about size or whatever is 26 x 1.95. I weigh just over 120KG, and the wheels say that at 50 PSI, the max load is 90KG... Does that mean that I should then increase the pressure, to increase the maximum load, or decrease it? I'm only using this bike for on-road/footpath riding, nothing offroad.

  • 3
    Remember your bike has 2 wheels, so your weight, plus your bike plus your load is (guess 150 kg total) That leaves 75 kg per wheel if they were evenly balanced, but most bikes put 60-70% of their weight on the rear . So, your rear wheel is about as heavily loaded as the makers recommendation, at 60%. Watch for potholes, and inflate to about 50 psi on the rear. Also, do use the search functions of this site. I note many good answers about tyre pressures and weights, like bicycles.stackexchange.com/questions/616/… – Criggie Apr 8 '16 at 4:29
  • You can reduce the stress on the wheels and tires by properly moving your body to account for bumps, you have a front shock, so you can be less careful with the front, but try to move your weight to the back (or even lift the front wheel a bit) as you approach a bump, once the front wheel clears the bump, shift your weight towards the front of the bike. – Kibbee Apr 8 '16 at 12:42
4

I weigh just over 120KG, and the wheels say that at 50 PSI, the max load is 90KG... Does that mean that I should then increase the pressure, to increase the maximum load, or decrease it?

The max load on a tire is restricted because higher load can cause a pinch-flat at a given pressure - and the max pressure is limited by the tire properties (and also by the rim strength).

So if you run your tires at maximum recommended pressure 50 PSI, you risk pinching the tube. If you inflate the tire more than 50 PSI, risk of pinch-flat goes down, but the manufacturer does not guarantee that the tire will not explode.

Ideally, you should have selected tires which are specified to bear your weight. In practice, this may be less of an issue because of at least the following:

  • the vendor might have indicated the "load" as load on just one wheel. Then, as said in the comment, your most loaded wheel is carrying just about 90kg.
  • 1.95" MTB tires are designed for MTB, so there is probably less chance of pinch-flat while riding onroad.

So answering your question: the pressure should be increased, but the tire specification limits the maximum safe increase.

  • Realistically speaking, one can safely exceed sidewall pressure by 20-30%. – Daniel R Hicks Apr 8 '16 at 12:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.