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I put a set of GP4000’s on my Trek 5500. I have only 800 miles on the set. While cleaning the bike today, I noticed that the rear tire is developing a flat pattern on the running surface. Not large at all but not the cone shape it began with - and still present on the front. I weigh 160 pounds and always put 110 to 120 PSI front and rear before every ride. Aside from perhaps being time to rotate the tires, (seems early) is this flattening out a normal thing? I presume I’m putting more tire on the road and thus increasing roll resistance. Actually I ran the rear at 120 until a week or so ago – went down to 110 to improve ride a bit.

I ride almost exclusively on a paved trail.the "pavement" is the tar and gravel method, so the surface is not exactly smooth, but not bad at all. Average speed would be somewhere around 16mph. thoughts?
 

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With 800 miles and it's just starting to get a square edge, thats not bad for a race tire IMO. If you rotate them now, and then rotate every 800 miles, you should get well over 2000 miles on the set. Just for reference i rotate my fortezza tri-comps every 500 miles and get 2500 miles on a set before the tread gets to thin. perfectly acceptable for a race level tire IMO
 

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So many issues

bboseley said:
I put a set of GP4000’s on my Trek 5500. I have only 800 miles on the set. While cleaning the bike today, I noticed that the rear tire is developing a flat pattern on the running surface. Not large at all but not the cone shape it began with - and still present on the front. I weigh 160 pounds and always put 110 to 120 PSI front and rear before every ride. Aside from perhaps being time to rotate the tires, (seems early) is this flattening out a normal thing? I presume I’m putting more tire on the road and thus increasing roll resistance. Actually I ran the rear at 120 until a week or so ago – went down to 110 to improve ride a bit.
A flat center, or "squaring" is how tires wear. The higher the pressure you run, the more the force is concentrated on the center of the tread and therefore the faster it wears down. At your weight, assuming 23 mm tires, you don't need 120, or even 110 psi - 90 front/100 rear should be fine unless you are forced to hit a lot of sharp pavement edges where you ride and are not good at unweighting. Rotating the tires is not a good idea, as you put your most worn tire on the front. A better procedure is to run the back tire until it's worn out, move the front to the rear and put a new tire on the front. Higher pressures can actually increase rolling resistance on rougher pavement as the tire "bounces backward" when it hits a rough surface. Plus, you lose comfort and traction with higher pressures.
 

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Worn tires and flattening profiles

bboseley said:
I put a set of GP4000’s on my Trek 5500. I have only 800 miles on the set. While cleaning the bike today, I noticed that the rear tire is developing a flat pattern on the running surface. Not large at all but not the cone shape it began with - and still present on the front. I weigh 160 pounds and always put 110 to 120 PSI front and rear before every ride. Aside from perhaps being time to rotate the tires, (seems early) is this flattening out a normal thing? I presume I’m putting more tire on the road and thus increasing roll resistance.
Like Kerry and everyone else says, a flattening of the tread profile is the normal wear pattern for bicycle tires. Whether it is worn out isn't whether the tread has flattened, but rather how much tread thickness is still there. Personally, I run most of my tires down until you can start to see the casing fabric.

As Kerry says, rotating the tires is usually not a good idea, because you always want your better tire in front.

Tires always "flatten out" (flex) at the ground contact point anyway, so the flattening of the profile from wear has virtually no affect on handling or traction. In actuality, the decrease in tread thickness, plus the fact that the tires have flex less to "flatten out" at the ground contact point, means that tires that have worn flat generally have less rolling resistance than brand new tires (this has been measured).
 

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After getting blasted by McM on the tubie thread, I'm going to agree with him here about not rotating tires. Move them from front to back and back to garbage; when your rear is showing threads, toss it, put the front tire on the rear rim and put a fresh tire on the front. Feels great and you'll get loads of miles out of the tires.

BTW, this is where tubies are a hassle...

chris
 

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bboseley said:
I put a set of GP4000’s on my Trek 5500. I have only 800 miles on the set. While cleaning the bike today, I noticed that the rear tire is developing a flat pattern on the running surface. Not large at all but not the cone shape it began with - and still present on the front. I weigh 160 pounds and always put 110 to 120 PSI front and rear before every ride. Aside from perhaps being time to rotate the tires, (seems early) is this flattening out a normal thing? I presume I’m putting more tire on the road and thus increasing roll resistance. Actually I ran the rear at 120 until a week or so ago – went down to 110 to improve ride a bit.

I ride almost exclusively on a paved trail.the "pavement" is the tar and gravel method, so the surface is not exactly smooth, but not bad at all. Average speed would be somewhere around 16mph. thoughts?
You're using GP4000s for riding MUTs and complaining about wear? This is a race tire! They wear fast. Get a Ultra2000-3000 if you want something that wears better.
 

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stanleybadcat said:
GP 4000 tires are manufactured with wear indicators. The indicator is a tiny hole in the tread compound. When you can longer see this hole the tread is worn to the point where the tire should be replaced.
Threads are a great wear indicator. When they show, your tire is worn out.
 
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