Tires, how MUCH can they help?

After six years of experience with GP4000s, I've had only one sidewall blowout, and that came after banging sideways into a curb while fiddling with a cleat, or otherwise not paying attention.

 

Like someone else here pointed out, in my experience same width tires, not much. But if you are replacing a thicker tire to a slimmer one, example 32mm to 25 or 23 mm. Yes you can gain 3-5 mph on an average( at least per my experience). This could vary greatly depending on the wind factor and the particular conditions of the road on that particular day. I ride 32mm regularly, not long ago I rode an Allez with 23s and I did reach a higher top speed and higher average. 3 mph average and 5 mph top speed faster. I think tire thickness does make a difference. If same thickness, I guess it's looking at the specific brands and what that particular tire is made for.( racing, endurance, puncture resistant, etc...)

 

Funny I have had nothing but Conti sidewall failures on all 3 sets (that's 6 tires that failed due to sidewall issues, one set was the GP4000, a set of Gatorskins, and the other a set of 4 Seasons), each a different model, of a road bike tire and these failures occurred long before wearout; and now what I thought I liked, was a set of Conti MTB Sport Contact tires that after just 2 years the sidewalls are brittle and cracked I noticed the other day, and those tires only have about 500 miles on them. I also had the same issues roughly 20 years ago with a set of Conti (can't recall the model). None of my other tires in 40 years suffered such a high degree of problems within the same brand.

For tires that cost more than most and to have those types of issues I'll never buy another Conti tire...just a personal opinion based on personal experiences. Speaking of experiences, it's also funny I hear a lot of people on forums rave about their Conti tires yet most of my friends who ever tried Conti's all had sidewall issues too...weird huh? Not so weird when you consider Conti's have the thinnest (almost paper thin) sidewalls on the market, and they're fragile on top of it. Maybe I'm weird for wanting a tire that will last till the tread is worn out and not having to pay $45 or so for a tire only to see it fail before it's half worn out.

If I had those issues with all tires than I would say it's me, but in 40 years of riding to have constant issues with the same brand...no it's not me. Being a tightwad that I am, I don't see the logic of spending $45 for a tire that lasts about 1800 miles when I can pay less (actually the average price I pay is low because I buy closeouts for $45 to $60 retail tires for $19 to $30) and have the tire last 4,000 miles.

Again, just my opinion based on my personal experiences.

 

Whatever speed increase you got from changing tires was probably more due to the type of tire than the width. I have a good pair of touring 700x35c tires on my cross bike with a fairly thick tread. This bike itself is pretty heavy and I sit more upright on it, looking at my averages commuting, I am maybe 2mph slower at worst. Rolling resistance for a larger, slick tire is pretty good compared to a narrow tire.

If you are running a knobby, stiff large tire - the difference to a narrow training or racing tire will be much greater.

 

Isn't the new logic actually that wider tires have LOWER rolling resistance due to less PSI at the contact patch?

 

While that is true it's only true up to a certain width, the current thought is once you go over a 700x25 you begin to increase that rolling resistance as the tire gets wider, thus a 28 will have more rolling resistance not less than a 25. I think there isn't a whole lot of difference between a 23 and a 25 or even a 28 but as the tire gets wider it gets progressively worse rolling resistance. I'm am talking about on the road not off road.

the contact point changes, from a elongated tread contact patch to a more rounder one as the size goes up.

Read this for more of what I know little about! : http://velonews.competitor.com/2012/03/bikes-and-tech/technical-faq/tech-faq-again-bigger-tires-roll-faster_209888

 

My point was that, all else being equal, changing the width of a tire will not result in huge gains. The data in the article Froze linked shows the differences being a few watts - not nearly enough to increase speed by 5mph.

 

Exactly why I posted that site. If someone was riding heavy 20 x 2.75 knobby tires with heavy thorn proof or slime filled tubes then switches over to a bike with 700 x 23 or 25 tires than I could buy a 5 mph increase due to weight, width, friction from knobbies, and air resistance against a fatter tire profile, but typically going from a 23 to a 28 won't be anywhere near that, maybe, I say maybe, you might see a gain of 1/2 a second in a 100 mile race, but a 1/2 a second could be the difference between winning and losing!

One of the reasons I bought a Lynskey vs the Motobecane (though this was a minor issue) was the fact that the Lynskey could use a 28 tire on it while the Moto only a 25, not a big deal thus a minor issue as I said, but if time goes by and people start to realize that a 28 could roll a tiny bit better than a 23 or a 25 my bike would be good to go.

Read that site I gave and read the letters, you'll discover that as the tire width increases there becomes a breakeven point and then after that the resistance goes up because of the additional weight a wider tire weighs due to more rubber and casing material, and the less aerodynamic it becomes due the width.

Also pay attention to the discussion on tire PSI, you don't want to run the same PSI in a 25 as you would with a 23, you have to run less which is why the Michelin tire pressure calculator is an important tool; see: http://www.dorkypantsr.us/bike-tire-pressure-calculator.html If you've never used this before use the middle, or 2nd calculator, enter your total body weight fully dressed for cycling and add to that your total bike weight fully ready to cycle, next enter the F/R weight distrubution factors (I personally like the second choice of 45/55) and finally enter your tire sizes. This calculator is based on a formula that has been around for many years, however you can alter the ratings to suit your needs but I wouldn't exceed 5 psi over or under the recommendation, some want a firmer ride and some want a softer ride so those ranges are there to suit that. Also pay attention to your tire's packaging or sidewall information, a few brands have their own recommended PSI range that won't match up to the Michelin calculator, and in those cases it's best to heed to the manufacturer's recommendations. I know my Vittorias came with a chart but that chart matched the Michelin recommendations.

 

This calculator from Vittoria offers a lot more variables, but also comes up with some numbers that, to me, seem very high. It also happens to disagree with the chart that came with my Pro4's by about 10psi.

http://www.vittoria.com/tech/recom-tyre-pressure/

 

That is weird because the box my tires came in showed a PSI that lined up with the Michelin calculator, however, that Vittoria calculator did not take the size of the tire into its calculations, so I can only assume the box did had it correct by taking casing, and size, then it graphed for the weight and psi to be used.

 

My Pro4's instructions lined up with the Michelin calculator exactly... but I think that's to be expected lol.