General Cycling Discussion - tire pressure

I have always had tires that say max pressure 110 or 120 psi. I am looking at some new tires and they say max pressure 145 psi.

This might sound like a dumb question but here goes.
Do I have to pump these tires to 145 psi?
My floor pump is good for 160 psi so that's not a problem at home. But when I have a flat out on the road I have a hard time pumping 110 and 120 psi tires with my frame pump. I'd probably have a stroke before I got to 145 psi.
Thanks.

The max psi is just that, the max psi that the tire should be inflated to. If you are a heavy rider or carry alot of extra gear with you then you might want that much air in the tire. Other wise back the psi down. Depending on your weight and the type of road you are ridding on should be the determining factor. Running the tire will let you roll faster but it will also wear the tire out faster. I would suggest contacting the manufacturer of your tires and talking with some one there.

Originally posted by RonH
I have always had tires that say max pressure 110 or 120 psi. I am looking at some new tires and they say max pressure 145 psi.

...I have a hard time pumping 110 and 120 psi tires with my frame pump. I'd probably have a stroke before I got to 145 psi.

I have a "telescopic" pump. When pumping my tires, I can fix it between my knees and use my leg muscles for that extra pressure.

(145? Dawg!)

:eek:

I have a set of tyres that are rated to 175 psig. I have, on a rare occasion, pumped them up to 150 psig.
Do you need to pump it up to the max pressure? How bad do you want your bike to ride??

You will never get it beyond 100psi with a small hand pump, but that will get you home. If you race, then a CO2 system may reach that pressure. If you tour, then a proper frame pump may help. Some carry pumps can be used as floor pumps and get significantly higher pressures.

Unless you are racing and wish to minimize rolling resistance, while sacrificing comfort and possibly traction, why go beyond about 120 PSI? I generally run about 100-110 in front and a bit more in back.

Some things on tire pressure.

Decreases in rolling resistance decrease with increased tire pressure. But the increment of decrease flattens out at around 90 lbs pressure. Generally 100lbs-110lbs is plenty for a road tire. As a word of caution, when on your bike glance down at the rear tire (and don't run into something). If you see a bulge in your rear tire where it hits the road, you probably need more air pressure. You don't want to get "pinch" flats. Pinch flats are caused by the rim pinching and puncturing the tube because of bottoming out on stones, bumps, etc. As a fix, you can either put more air pressure into the tire or ride a bigger tire (one more suitable for your weight). Many riders ride overly small tires. A friend of mine, who is about 220 lbs was riding 20 mm tires and had to do a fast stop - his skid wore away his tire and caused a blow out. He switched to 23 mm tires and was amazed at the improvement in ride.

As far as maximum pressure in a tire, I have heard that the tire manufacturers set this by inflating the tire until it blows off the rim. They recommend a pressure that is about half of the blow off the rim pressure. Of course, that could be a myth. But it is a fact that you can often get away with inflating tires well beyond the suggested pressure. I just don't think it is a good idea.

If you go over 120 psi, don't use a lightweight tube.

I am not an expert, but I always try and be pompous enough to sound like one, so you have been warned.
It appears that the lawyers for the tire manufacturers want a specific max inflation and it doesn't matter what the tire will actually take.
I used to be the black hole of inner tubes. About 3 years ago a racer told me that the tire I was using should be at 10 pounds over what the label said. He suggested that I run them at 135 instead of 125. He said that the rolling resistance would be less and my incidents of flats may go down.
He was right on both accounts. In the last 3 years I have had 3 flats, well 4 if you count the Conti GP 3000 blowing out the side seam (a common problem). This is with around 17,000 miles and many different tires.
This has been offered in the "for what it's worth" column. If you try this, let everyone know how it goes.

If you want to experiment with high pressures, make sure your rims are hook-beaded and sound.