Will any tire of a given width feel "hard" at it's highest recommended pressure? I've always pumped up my tires to the highest listed pressure (usually 80) where they were extremely hard and offered little rolling resistance.

If I get a 700 x 45c tire and pump it up to it's highest recommended pressure, will it be hard like my 700 x 35 at it's highest pressure or will the wider tire feel "mushy"?

Can a fatter tire be both hard and more comfortable or is a comfortable tire necessarily a softer tire?

I'm now middle-aged, overweight and have some orthopedic issues so I'm interested in the more comfortable ride I've read that fatter tires give but I also absolutely cannot stand tires with a lot of rolling resistance. In the past, anything less than max pressure feels like a flat tire to me. I'm considering Marathon Supremes or even Big Apples but I don't want to shell out big bucks only to find that even at the highest pressure the tires have a mushy ride that I hate.

You´ll probably get as many answers on this one as there is riders. Some of us over-inflate and regards it as the best way to make the bike go faster. Even att recommended pressure we sense a squishy rolling resistance (or we´re just a bit neurotic and senseless to how bumpy the ride gets!). A wider tyre should take up shocks better, even when pumped hard, but I´m not sure as I never run fat tyres. Its a bit mathematic (your weight, type of tyres&rims), the feel of the bike, type of surface, riding style and so on. I´m generally go 20 psi above recommended max pressure.

Interesting. I'm like you in that I prefer hard tires but I've been afraid to go higher than the stated max, especially on the ten dollar tires my dad put on this bike! My Trek 7.2 FX had tires at 80 psi and they took sharp corners fine. The 730 has tires at 75 psi and the front one feels flat when I take a sharp corner. I guess I'll bring it up at the bike shop when I take it in for an overhaul.

For more comfort I inflate my tires to the lowest recommended pressure. My current set of tires is rated at 60-80 psi. I haven't been able to tell much with regards to rolling resistance at 60 or 80 but I can definitely tell the ride is harsher at 80 so thats why I keep them at 60.

If your rear tire is not deflecting (squashing) as you ride, it's overinflated.

You will get used to the mushy ride feeling if you give it a chance. Then you'll appreciate the ride quality. I've experienced this and you have to resist the urge to pump all tires to the max because you'll be missing out on tire life, traction and most importantly ride quality. You might sense something 'wrong' when you have a forgiving ride, but over time every part of your body in contact with the bike will enjoy it, plus your wrists, back and neck as well.

More pressure required:
- rear tire
- heavier rider
- narrower tire
- optimized for dry smooth road

Less pressure required:
- front tire
- lighter rider
- wider tire
- optimized for off-road

75 PSI should be plenty stiff on any tire over ~32mm wide or so. I use 700X32 tires and pump them to 75psi and I weight 260 lbs and it seems to work ok.

What are you measuring pressure with? I have heard that pump-mounted gauges can be unreliable but that is what I use and my tires feel plenty stiff at 75 psi

I'm measuring the pressure with a pump-mounted gauge. I kept my 7.2 FX 700 x 35's at 80 and they were fine. These 700 x 35's at 75 feel flat when I turn a sharp corner. It even sounds like I'm turning a corner on a flat! I'm hoping it's just that they are really cheap tires. After I get the money for an overhaul, I'm going to save for some good tires and hopefully this won't be an issue.

75 PSI should feel just fine, even in the cheapest of tires. You should confirm it is the tires causing this sensation before you spend any money.
Cheap tires are generally more rigid than expensive performance tires - it is the energy required to flex the rigid casing that gives higher rolling resistance. I don't know if this difference will actually make the tire feel stiffer when riding... I'm inclined to think not much difference.

Two questions:

1. How much do you weigh?
2. how wide are the rims on which the 35mm wide tires are mounted? If the tires are too wide for the rims then they form an 'omega' shape that is more prone to squirm under side loads.

I used to think that, but then I rode a 700x35 Kenda Kross Supreme and found out it is not univerally true.

This is an old cross tire first developed in 1998, and it is now out of production but available cheap through various sources. It is really terrible on paved surfaces and hardpack. The tread is open for mud and loamy soil, and the blocks are very squirmy. You can feel them moving around when you turn whether high or low speed.

And this is at 85psi, the max rating on the tire. It's worse at lower pressure.

If you don't have a knobby, though, I would think that few tires would squirm at high pressure.

A wider tire pumped up to its maximum recommended pressure will typically feel harder than a narrower one when you try to squeeze it by hand. Counter-intuitive, but this is because it actually takes more force to get the same pressure reading in a wider tire, yet the maximum recommended pressures usually don't differ that much between tire widths.

As far as the mushy feeling you get when riding at a somewhat lower pressure, that's got little to do with the actual rolling resistance and speed you'll be able to attain. A harder tire will feel like it's moving faster because you can feel more of the road moving under you.

I recently went from the stock 45c tires, filled at 50psi, to 28c tires filled to 90psi (125max psi) Wow, big difference on how she rolls, but I now have to really slow down when hitting the sections of horribly paved road. Really feels those bumps and cracks in the pavement now, but wow she really wants to fly over smooth pavement, so its always a trade off. Still, I think the rolling qualities of the new tires overcome the cons, so I'm keeping them on.