Fahrenheit531 

My bike plus myself typically comes in below 170 lbs (~77 kg).
The Sacred Chart of the 15% Tire Drop puts my recommended pressure at about 80/70 psi for 25mm (I typically run a bit lower) and 55/45 at 32mm.

With my pressures already relatively low and road buzz not a real issue as a result, do I stand to see substantial gains in comfort and/or speed at 35mm-plus? My instincts say no. But any opinions, science, and/or personal experience would be welcome. The tire debate is pretty lively these days; maybe this is a new angle on it.

General Geoff

I run 40psi on 40mm wide tires and I weigh about 205 fully clothed + bike of ~25lbs, for a combined 230ish. You should be able to run 30-35psi on 40-45mm tires without issue. Would be super compliant and comfy.

HTupolev

The really important question is what surfaces you're riding. The big benefit of going wider is that it allows tires to behave and perform better when pumped squishier. If your current squishiness is adequate for the riding that you're doing and your tires are still firm enough to be well-behaved under your weight, then fatter won't accomplish much. If all your riding is on well-maintained smooth asphalt, there's probably not much to be gained with >25mm tires. If you've got very rough chipseal, this might be another matter.

Regardless of what width you go with, remember that everything else about how the tire is made is of crucial importance. A fast fat tire can perform far better on the road than most people think, and a slow narrow tire won't perform well on the road just because it's narrow.

rm -rf

Yes, exactly.

My 38mm Compass tires were awesome on new, rough chipseal, and perfect for a crushed stone rail trail. 38 psi front and 45 psi rear -- a plush ride.

But I switched back to 28mm for my more reasonable road rides. (one reason was the over 200 gram difference per wheel between the tires, including lighter, smaller tubes.)

canklecat

Ditto, road surfaces and overall conditions, and type of bike. Adjusting pressure alone won't necessarily improve things. Depends on the tire.

I'm 160 lbs and vary tire pressure on various bikes to suit conditions and my personal comfort that day. With old and recent back, neck and shoulder injuries I vary things to suit myself on any given day.

Usually I keep the road bike tires around 80-90 psi, but if my back, neck and shoulders feel good and the roads are expected to be smooth I'll pump up to 100 psi or so. It's just a bit faster and/or less effort on smooth pavement. For chipseal, definitely lower pressure. That's been a good approach with Schwalbe One V-Guards and Continental Ultra Sport tires. Not so good with low end Vittoria Zaffiros, which just felt sluggish and still not particularly comfortable at lower pressure.

I just switched my favorite hybrid for casual group rides from 700x38 cyclocross-type tires (usually around 50 psi, a little lower on gravel) to 700x32 urban tires at around 65 psi. Big difference in feel and comfort. I'm already missing the bigger, softer tires, especially off pavement. But I needed the narrower tires to suit the fenders I already had in the closet since we've had such a rainy autumn and the winter is looking to be warmer and wetter than usual. I may try the 700x32 tires closer to 50 psi to see how they feel, but it still won't match the feel of the other tires. Big differences in sidewall pliability, tread thickness, etc.

MikeyMK

At 65kgs i went from a 1.5in tyre to a 2.35in tyre and never looked back. But then i only ride MUPs.

surak

I weigh less than you, OP, and only realized now that there's no point in me running wider than 25mm in the rear after swapping a 28 for one to fit my new fender. I never feel a thing in the back as long as it's on a road, however crappy. I can just let my legs absorb the bumps.

Front tire vis a vis arm comfort is a different story. I'd go as wide as possible but definitely wish my road frame could clear more. When I'm captaining my first tandem with 26x1.75 tires, I marvel at how much smoother it feels over the same roads and regret not going even bigger. I have 26x2.0s on the way for my most recent tandem acquisition.

On other bikes, I've run 32mm and 37mm, and even though the tires weren't as high-end, I could still feel a difference. Perhaps a carbon bar and full carbon fork would mute the benefits, but I have no experience with either.

CliffordK

I suppose I'm a bit traditional, and every time I try wider tires, it just seems to increase rolling resistance (or at least if feels that way).

But, I think you're right. If 28mm tires are good for someone 200 lbs. Then 25mm tires should be good for you at 150 lbs.

Fahrenheit531 

Okay, thanks all. These posts mostly confirm what my instincts were telling me. I hadn't included road surface in my calculations, but most of what I do is on roads in good repair with only occasional would-be cobbles (aka shoddy chip-seal). My 25s ride beautifully (Continental GP Classics), so maybe I'll just outfit the one bike running 32mm Paselas with some Compass in the 28mm range and call it even. Thanks again for the insights!

General Geoff

Buy a fatbike and run 4psi

Sy Reene

A good amount of tour riders are at around your weight. I'm sure they've picked up lots of speed all going to 35mm tires.

AlmostTrick

It seems to me that tire size logically should relate to rider size (weight). So yeah, light weight riders can easily run lower pressure and safely get a great ride on a narrower tire than big riders can. No need to go wider. At 130 pounds Compass 28's (at 40-45psi) are my favorite. They are quite light and only measure about 26 on my rims.

Even though I could, I won't run any narrower because I don't like the increase risk of crashing due to getting caught in a rut or hitting any other road hazard.

What doesn't make any sense to me is heavy riders on 23/25's pushing 120psi. Oh well, to each their own!