Road Bike, Cycling Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter · #1 ·
I need some information from you guys out there. I am5'10" tall. i weigh 210 lbs. I have bought every brand tire on the market possible today. Question i inflate the tires at least 5 lbs less than the maxium tire pressure required by manufacture. i ride the tires approximatly 200 miles when that evil flat area apears in the middle of the tire. Am i under inflating the tires, or is it my weight. is anyone out there, that is my weight having the same problem. I then rotate the tires front to back, and there it is again, sometimes sooner. Depending on the brand tire.
 

·
Registered
Joined
·
11,474 Posts
Perfectly normal.

The flat area appearing on a rear tire after 200 miles is perfectly normal. Some tires (softer rubber competition) get it a little earlier, some tires (harder rubber touring) a little later. The flat area is not going to affect performance one way or the other.

FWIW, the maximum tire pressure number printed on or molded into a tire is not a "required" pressure. It's the pressure you exceed at your own risk—in other words, it's a lawyer number. There are good tire charts out there listing proper pressure by tire size and rider weight.
 

·
Registered
Joined
·
1,846 Posts
+1 Wearing the tread off the center pretty quickly is normal. There's very little surface area at the peaks of the tread and so they wear quickly until more contact area is established, then wear slows down, and the tire gives you the other 90% of it's service life.

I disagree with the "lawyer number" characterization, but agree that the molded pressure number is the tires maximum working pressure, the same way it is on auto tires. Your optimum pressure should be less than that number (or buy either a higher rated or wider section tire) and is determined by your weight and the tire's cross section.

Unfortunately rider weight is a bigger relative variable on bikes than it is on cars, so there's no recommended tire pressure sticker (and anyway there's no driver side door to affix it to).

Here's a link to an excellent article about optimizing pressure based on weight. What id doesn't say explicitly, but can be inferred from the chart is that heavier riders are better off riding larger section tires than running narrower tires at super high pressures. I use the chart to find the tire section appropriate for the load at 90-100psi.
 

·
Registered
Joined
·
21,542 Posts
Flat out

spinnertsaf said:
I need some information from you guys out there. I am5'10" tall. i weigh 210 lbs. I have bought every brand tire on the market possible today. Question i inflate the tires at least 5 lbs less than the maxium tire pressure required by manufacture. i ride the tires approximatly 200 miles when that evil flat area apears in the middle of the tire. Am i under inflating the tires, or is it my weight. is anyone out there, that is my weight having the same problem. I then rotate the tires front to back, and there it is again, sometimes sooner. Depending on the brand tire.
Tires are worn out when the casing threads start to show through the center of the tread rubber. The center will go flat long before the tire is worn out, and the higher the pressure you run, the faster the tire will wear out because the width of the contact patch decreases along with the amount of rubber in contact with the road. With your pedaling force is constant, the force per unit area on the tread rubber is higher, therefore the scrubbing action to remove the tread rubber is higher, and the tire wears out faster. Run the lowest pressure you can that will still prevent pinch flats. At your weight, you might want to consider wider tires (25mm or 28 mm).
 
1 - 4 of 4 Posts
Top