Bicycle Mechanics - Still Another dumb Newbie question!

Looking at tires in my Bike Nashbar catalog, I keep seeing the designation "tpi". What does that mean? PSI is pounds per square inch, (right?) but what is TPI? Duh! Also, reading the various mechanical section postings, many of you in the know like the Conti GP 3000 road tire. Bike Nashbar wants $46.00 apiece for them! What are they good for? 100,000 miles? Isn't there a more economical alternative? I'm looking for reliability, not speed. Thanks in advance for your valued input.

I don't know how this relates to tires, but I'm pretty sure it stands for threads per inch..
For example if you get a 24T or 24TPI axle, then it has 24 threads for every inch.


[EDIT]
Here you go, I looked it up and found it on another forum..

It's the thread count (Threads Per Inch) in the woven tire casing. More thread equals a smoother rolling tire, because it's a tighter weave. It also makes for a better handling tire as well, for the same reason. Check the bead too, wire is heavier compared to Kevlar.
Posted by STP a 42 year old riding a K2 Razorback from Palmdale on 02/14/02

The TPI is, as stated, "threads per inch". To the best of my knowlege, it has absolutely nothing to do with the ride that a tyre will give you, but rather, is a decent indicator of how resistent the tyre will be to punctures. 24 TPI is probably the equivalent to rough burlap. Some tyres advertise as little as bout 150tpi, still not a very fine weave. My Tufo S33's use a belt with 305 tpi, a very tight weave, and a tyre that is nearly puncture-proof. They also make a severe-duty tyre with a casing of 440 tpi, but that model is quite expensive ($65-70 each).
As far as an economical alternative-yes, there is. You can buy cheaper tyres from, say, Chen Shin Tyre, or you can wait for your tyre to go on sale. From my experiences, Continental is rarely worth the extra money-they wear too fast, cost too much, and puncture too d@mn easily.

The Continental training tires such as the Ultra2000 (http://www.conti-online.com/generator/www/de/en/continental/bicycle/themes/tires/race/ultra_2000/ultra_2000_en.html) have considerably more rubber than the Grand Prix and will wear pretty well in my experience. Literally a case of "your mileage may vary," of course, depending on what you ride on, your weight, whether you occasionally swap the tires front-to-back... At any rate, these are the road tires I pick.

The Continental rubber itself, at least the "standard" black rubber on their German-made ones, seems highly cut- and puncture-resistant in its own right. And I've had a fair sample of them to observe, since I used to sell a lot of them. :)

Between precision Tutonic racing tyres and Chinese knock-offs there is a wide selection of good, tough mid-range rubber to chose from.
Im using Panaracer Pasela and Vredensteins and both seem to work well. Like most things, the sweet spot of the price/performance curve is to be found near the middle.

You can find the tires for less then that, I purchased my last set of tires from roadtiersdirect, very limited selection I got the vredestein tires been working great and I like the higher pressure but they have the gp 3000 for 32.95

TPI can be a good indicator on tire quality, but I would never use one variable as my sole reason to purchase a product.

As with most things in life, with tires you get what you pay for. However, as tires are frequently designed for specific applications, purchasing a $50, ultra light, time trial tire for daily training would not be a good value. Also, more expensive tires are frequently light, racing tires, and are not always a good choice for daily riding - i.e. they wear quickly, though they may be sticky and light.

I suggest you review manufacturers' website catalogs to find out the specific applications of tires and then match your application (touring, racing, training, etc.) to the manufacturer's intention - balancing your budget along the way.

I ride GP 3000s and they've been bulletproof, which I demand. They're also light and sticky, though they wear fast.