Tires "Scalloped"

PGlaves said:

If you set the correct cold pressure at 20C (68F) and none leaks out the pressure will remain correct as the tire heats up and cools down. If you set the adjusted pressure per the chart at ambient 100F if temps cool down to 68 by morning you will find the recommended pressure within 1 psi. And that goes for any increased or decreased temperature.

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Just so I'm clear on this, as it's been discussed a few times in various threads.

If my garage temp is 100 degrees, I should be setting my tires pressures according to the chart instead of putting them at 36/42 as I've been doing? I should be setting them at 39/45? And conversely, if it's 40 in the garage, I'd be dialing in 33/39?

Thanks, I thought from other threads that I was supposed to ignore the chart and just set recommended cold temp pressure.

BC1100S said:

Sorry, you're wrong. Did you even read the link I included?

One inflates one's tires dependent upon the ambient temperatures in which you are running. If one is running in 100F temps then one might inflate one's tires to 42 psi or whatever the bike's manufacturer recommends. If the next day one is running in 68F temperatures, the tire pressures should then be adjusted (cold) for that temperature.

But....you can do whatever it is you like.

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I read the link, and it clearly does not say what you advocate. The tire pressures in the manual or on the tire are based on 68 degrees and the tire being cold. A hot tire and a cold tire in an ambient condition of 100 degrees are going to have significantly different pressure indications.

BC1100S said:

Sorry, you're wrong. Did you even read the link I included?

One inflates one's tires dependent upon the ambient temperatures in which you are running. If one is running in 100F temps then one might inflate one's tires to 42 psi or whatever the bike's manufacturer recommends. If the next day one is running in 68F temperatures, the tire pressures should then be adjusted (cold) for that temperature.

But....you can do whatever it is you like.

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Yes I did--the information provided is incomplete and misleading, which is why you're misled about this. The problem is that tires must be able to accommodate huge swings in ambient temperature in the course of all possible rides one can take, and tires must be able to cope with that. Now if you lived in a steady state temperature of 100F all the time, I think you should be fine to set pressure to 42/36, but that is not what happens in the real world. For example In our ride to St George UT a few years back we left at 58F, and arrived at 112.9F. Had we parked the bike for 2h in that temp, then adjusted PSI to 42/36, by the time we got back up to elevation and evening ambient was back down to 50F and our tires then would have been under-inflated to around 36/30, which for a 650 lb bike would have not particularly safe for the loads involved.

Google the idea and you will see VIEJO followed the recommended procedure for setting tire pressure-adjust by 1 psi for every 10 degrees +/- 68F ambient.

ncpbmw1953 said:

Google the idea and you will see VIEJO followed the recommended procedure for setting tire pressure-adjust by 1 psi for every 10 degrees +/- 68F ambient.

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I appreciate your response and I will agree that up to the MAXIMUM RECOMMENDED PRESSURE embossed on the sidewall, your idea has merit. I neglected to state this in my first response .

pkpilot said:

I read the link, and it clearly does not say what you advocate.

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The comment in that link is ambiguous because it does not say what 'adjustments' are which is in this statement: "Ensure that you make adjustments if you take the pressure after riding, i.e. with "hot" tires." The adjustment they are referring to but don't state is: +/- 1 psi for every 10 degrees F from 68F.

brownie0486 said:

Just so I'm clear on this, as it's been discussed a few times in various threads.

If my garage temp is 100 degrees, I should be setting my tires pressures according to the chart instead of putting them at 36/42 as I've been doing? I should be setting them at 39/45? And conversely, if it's 40 in the garage, I'd be dialing in 33/39?

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That is correct.

PGlaves said:

That is correct.

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Thank you sir.

I started a post some time back on this and most people discounted the idea. I'm going back to the chart airing up the tires.