4000S 23mm is pretty good. There are some potentially faster options like the Supersonic 20mm, depending on the wheel, wind etc. But the supersonic has no puncture resistant belt in it.

The 4000S has decent, but not not top rolling resistance. However is has magic aero properties on all of the modern, wider aero wheels. This, combined with good durability is making it a favorite tire right now.

There is also the Attack, which is a little bit narrower, maybe better CRR, and better aero at low yaw.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

4000S seems to hit that perfect medium on ALL performance indicators. Aero, rolling resistance, ride, grip, durability, puncture resistance. The last 2 make it good enough to train on as well as race.

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TrainingBible Coaching
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FYI... the magic aero properties go to hell long before you've used up all the tread. So if you want to race on the GP4000S, it's best to use new ones. Also the aero goodness is mostly for high yaw, which may not describe your conditions.

I still think the 20mm SS for narrow rims, and for wide rims the 22mm Attack or 23mm SS or maybe even the 20mm SS are the fastest choices for *racing* tires... for most conditions.

I was recently looking at the Flo website and they stated that with wider wheels the GP4000 saved watts over every other clincher in their testing. I would assume that is the case if you are running firecrest or hed c2 also.

Per rruff's suggestion, I went from Gatorskins (came on the bike I bought) to 4000s'. I could not get past the 400 mi (or so) wear life for the SS, which he suggested as tops.

I'm not a FOP AG guy...yet...so 4000s' were the right choice for me, for the money. I can tell you I was skeptical of the speed gains but I think it really helped me in my last race. While my time was slower overall from my previous race, the course was different (more hills and a lot of headwind in the last 6 miles) but I finished 3rd in my AG in the bike split. The previous race I was 14th out of 24 in the bike. I was a "bit" fitter for this race but I think the tires probably gained me at least 1 mph - per rruff's prognostication.

Probikekit had them on sale for $28 a piece last week so I picked up 2 more sets. Might want to check there.

Cool thanks Jmott, gonna pick these up as we speak.

That's interesting... after how many miles do you suggest this occurs?

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thanks grabbed them from probikekit

I think Josh at Zipp mentioned that the aero goodness deteriorated measurably after a few hundred miles... but this is true of other tires also.

Just saying that if you believe your squared off high mileage tires are aero... they ain't.

Frankly I'm skeptical of the high yaw wheel data ... I suspect that it is easier to replicate in the tunnel with a very steady airstream, plus it's where those expensive carbon wheels look good, so it is what the wheel makers publicize. And I rarely race in high yaw conditions anyway. Low Crr and good low yaw aero works for me.

I've used the same set of gp4000s for the past two seasons.....18 races.....close to 400 race miles.....mostly OLY and a few Sprints. I like them......and have no problems.....flats, etc, using a Zipp 900 on back and Zipp 404 on front.....23mm on both (Cervelo P4). Pretty much only use bike for races.....maybe have 500 total miles on them (use another bike for limited road training). Are you saying I would still benefit by getting a new set before next year's schedule starts with this kind of mileage on them? And to others who use these tires......how often do you change out and do you notice a difference?
PS.....was actually thinking of trying the Attack/Force 22/24 combo next season just to experiment......any new thoughts/advice here?

fronts will last a lot longer, rears will wear much faster, ie square off. if you have noticed it is squaring, it is likely well past the point of being aerodynamically beneficial.

Ideally you get a new pair of tires about 1-2 weeks before a A race, and use the worn tires for trianing between or B races, or rotate them to set of training wheels. Rotating tires is also good practice for changing flats.

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500 mi would be past optimum anyway. I'm assuming you have another bike you could put your old ones on?

Or just don't sweat it. If you haven't picked all the low hanging fruit and optimized your drag in other ways, then this is not the next thing on your list to worry about...

The Force is a pretty fat tire. I'd run the Attack front and back if I wanted more puncture protection than the Supersonic provides.

BTW... if anyone tells you "they notice a difference" it's in their imagination. Even relatively huge real differences can not be reliably *felt* in controlled tests, but the wind tunnel and stop watch tell the truth.

I have wondered whether a Vittoria would be a better tire for rear on frames with a seat tube that provides a significant "shroud". That would put most of an aero tire effect on the trailing edge of the wheel where it might not matter much. The Vittorias tend to have a slightly lower Crr while still maintaining a puncture strip.

Sorry to butt in, but after reading this thread, I guess it causes me to question if I need to pick up a new set of tires before IM FL. I have about 375 miles on my GP400S'S. Should I switch out to some new ones for the race?

Hey rruff, i think you are conflating what josh said about the attack and the 4000s a little. Obviously squared off tires aren't aero but what josh said was that an attack after 300km was as bad in terms of aero as a 25mm 4000s; but that after 500km a 23mm 4000s only adds about 10-15g of drag.

His statement was that the 4000s keeps its aerodynamics better than other tires. I think that either way, I wouldn't sweat tire wear on a rear tire in terms of aerodynamics.

Here's Josh's comment http://forum.slowtwitch.com/...um.cgi?post=4344867;

Got it... but still, 300 miles and the tires are significantly worse. Plus, if you are riding in the 15+ deg yaw zone, you are either going slow or you have some strong crosswinds to deal with.

I've tested several Attacks and they test a hair better than the Vittorias on average, and the Supersonics a little better yet. Also, IME the Supersonics are as puncture and cut resistant as the Vittorias... but the tread doesn't last as long.

On the rear tire the important part for aero seems like it would be how the flow combines behind the wheel. The Vittoria has that side lip that probably doesn't help there.

Ehhh, to me its a coin flip. You seem to be advocating using the Attack for 200 miles for a little more speed versus saving the money and losing a handful of grams for 3x the race life of a 4000s.

I agree that manufacturers tend to point at high yaw too much but this decision is really a speed versus cost thing. I think lots of people would rather get 2-3 times the life from their race tires and lose a few seconds. Heck I'd probably advocate moving the front 4000s to the rear for a few more races. 600 miles is really not many miles.

Of course... this is serious hair splitting. 99% of STers probably have more important things to worry about regarding their aero performance.

Reading the above makes me wonder if I'm doing something special that makes them last as long as they do. My trainer-bike with ZIPP 202's (sometimes mount my race-wheels ZIPP 808 also with GP4000s-25mm) have GP4000s 25mm on them and have each covered >1500km (let's say well over 900mi) and still look to be in perfect shape. Not the least sign of wear or squaring or whatever. I've got a new tires laying around and just for sanity-check, I mounted it last week on 1 of the ZIPPs and tried feeling any difference between the new and any of the "old" tres, and I can't feel or see a difference.

I must admit though that I typically run them at reasonably low pressures (90-95PSI max). My disc has the GrandPrix TT tires mounted and I've covered something like 600km on that one and apart from a few little "gaps" from very small stones, that tires also looks to be in perfect shape.

All tires are mounted with butyl tubes, only for races I will mount latex ones for that special race feeling.

S.

I'm not surprised that you don't have squaring after 1000 mi... even the rears last near 3000 miles for me, before the tread is gone.

I think what happens fairly early is that the casing stretches a bit and the tire becomes wider and more round. Plus the tread *is* wearing more from the center of the tire, even if it isn't that noticeable.

Just the front, and only if it looks like it has been worn flat. Often you can still see the seam where the rubber injects after just 375 miles though

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Yea, it's the safest bet. I've raced on the Corsa Evo, 4000s and Supersonic. All 23mm with latex. I prefer the Supersonic over the rest.

The Evos cut like mad and the 4000s feel dead. I know the Supersonics do not have a belt, but they roll really nice on decent/good roads. I figure if something is going through the tire, a thin belt won't stop it. If a race had poor roads, I'd go back to the 4000s if it was an important race.