More Tire Talk

The most recent Guitar Ted Podcast was about tires.

About a week ago, I wrote up a mini-series about tires and the questions folks have about them which end up, generally speaking, in a discussion that looks a whole lot like a discussion about religion. 

The tire theme is a VERY popular subject on the podcast I do, on Riding Gravel, and almost anywhere that there are more than two people in a forum online. I guess tires matter to y'all, and so I keep talking about them and writing about them here and elsewhere. 

In the latest "Guitar Ted Podcast" episode, I mention in the podcast that "air pressure is the most misunderstood thing about tires." I mentioned this in my mini-series briefly by saying the following:

"Tire pressures are another easy to understand difference here. But these settings should always change with weight, terrain concerns, and with regard to the weather conditions. Tire pressures are "set and forget' for many riders, but this is an oversimplification and those folks are cheating themselves of the best results that they could have. But then again, if you don't care......"

I made a mistake in that quote by saying simply that "Tire pressures are another easy to understand difference here." when I should have said "....easy to understand once you examine the reasons why." The thing is, most riders don't think about this, so they misunderstand, or maybe more accurately, are ignorant to, the differences tire pressure can make for a rider. 

In other words, you should carry a gauge and a pump for reasons of changing tire pressures more than you should for flat repairs. I said it on the podcast, but think about any motorsport: They make micro-adjustments to tire pressures all the time to effect various performance outcomes. We cyclists even practice this with our 'more sensitive to air pressure changes' tires such as fat bike tires or "plus sized" tires. (If you aren't doing pressures adjustments with fat bike tires, YOU NEED TO!) 

A tire's construction should inform tire pressure choices.

Not only should you be experimenting with tire pressures, you should also understand that how a tire is made should inform which tire pressures you should use. 

For instance, a tire that is simply a folding bead tire with no extra puncture protection belts or that is not tubeless can be run at a higher pressure and have a certain performance outcome. Now, switch that tire out for a puncture protected tire that is tubeless ready. What should you do? 

If you understand that puncture protection belts and that tubeless construction techniques make a tire sidewall stiffer, then you might understand why a lower pressure than you used with the first tire will help you reach the same/similar performance outcomes of that first tire. 

This can be illustrated by a tire I used when testing 29"er products from GEAX, (now Vittoria). I had run one of these tires which was not puncture protected and was used at about 28psi. When I got a hold of the armored tire in the same size and model, I had to lower my tire pressure into the upper teens to realize similar riding characteristics to the previous tire. 

Now, that is obviously an extreme example, but it illustrates that choosing an air pressure to run tires at arbitrarily and loosely based on the flawed maxim that "higher pressures roll better", is bad thinking. It is a mistake that many riders still make. 

Now, you may be thinking, "Okay Ted, but your examples are all for MTB and fat bike tires which you say are more sensitive to air pressures. What about gravel tires?" 

Even gravel tires, like this 40mm IRC Boken, are sensitive to air pressure changes.

Gravel tires respond to changes in air pressures also. The difference is that the amount of change is more to effect a change than it is with high air volume tires. 

So, for instance, my 'plus sized' Teravail 29" X 2.8" Coronado tires can be noticeably different in ride feel when changing from 18psi to 20psi. You can feel a BIG difference. Now, changing a gravel tire's pressure by 2 psi makes no discernible difference, but it makes a difference. If you want a discernible difference, you'll likely have to change the pressure by at least 5psi. So, I like to say that your "window" of hitting it right for what you are looking for is wider with a gravel tire than it is with a fatter, plus sized tire, or even a fat bike tire, where going 1psi either way is noticeable in terms of ride performance in snow or mud. 

Okay, so tire construction will help you choose tire pressures, and making changes in air pressures experimentally will help me dial in a "right" pressure for me and my riding style. But when you arrive at :The Pressure", you're done, right? 

Wrong!

 Conditions also will dictate what pressures you should be running. Are the roads you are going to be riding fairly clear of loose gravel and hard, or are these roads littered with fresh gravel? You need to adjust pressures accordingly. I mean, obviously, if you don't care, you can ride whatever pressures you want. This advice is for anyone wanting to arrive at the best performing tire and best ride feel that they can get. 

So, think about all that and see if it makes sense to you to try different air pressures or not. The bottom line? Just ride. You are better off riding your bike, no matter what the air pressures are, than not riding and over-thinking the minutiae of tire pressures. 

Thanks for reading Guitar Ted Productions!