I ride a 2014 Kona Unit (rigid ss 29r), currently with the stock 2.25 Ardents on front and back. I ride some fairly gnarly stuff here in SoCal, and also lots of loose, dry stuff over hardback. Thinking about bigger tires for a little more cushion and grip. I know lotsa folks like a fatter tire on the front than on the back--for example, I could put an Ardent 2.4 on the front and leave the 2.25 on the back. But why not put 2.4s on both? Is it just a rolling resistance and/or weight issue? The way I ride a few extra ounces isn't gonna matter. How dramatic a difference in rolling resistance would there be?
(BTW, I currently run tubes. I'm pretty light--I weigh about 134lbs and run around 16.5psi front, 17.5 psi back. Knock on wood, I've never flatted on this bike in 6mos of riding 3-4 times a week with no shortage of rock gardens, so I haven't bothered to go tubeless.)

Regarding rolling resistance on trails, the 2.4 won't be any worse.

Some riders prefer the front tire to have more grip than the rear, but if you're already riding the same tire on both ends, then probably you can keep doing that.

Thanks. Yeah, I wouldn't mind more grip on the rear, that's for sure. I lose rear wheel traction on climbs sometimes with the ss, trying to power up them as fast as I can. I know it's a technique thing too, but even a little extra grip would be quite welcome.

You usually have more room for a larger tire up front. Going tubeless if you haven't already also softens things up a bit on a rigid.

I have the unit and ditched the ardents for 2.4 f/r. Chunky monkey front and mountain king rear. Extra squish is nice, find the climbing and braking of the mountain king much better than the ardent. The chunky monkey is a great tire, grippy and squishy. Havnt noticed any difference in speed, rolling resistance with the 2.4 tires.

It's mostly a weight Issue, a lighter rear wheel is like a free power booster on climbs and acceleration.

Traction is a bit less of an Issue out back as many like me, like a looser rear end,, As long as you can climb without slipping.
Fatter tires let you run a little less PSI for a little less rolling resistance, They float in sand better and they look cooler

The less rolling resistance thing,,, Lower pressures let the tire deform better/faster over small bumps,
More pressure makes the tire bounce over things and that takes more energy away from the rolling Inertia.
Maintaining that Inertia lets you conserve energy.
All of this depends on how you ride, your terrain, etc....

I run a 27.5 X 2.35 out front and a 2.25 out back and YES I can feel a handling benefit of a little lighter and skinnier out back...
But It's a by degree's thing,single didgits, I'd be fine running 2.35's at both ends...
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(BTW, I currently run tubes. I'm pretty light--I weigh about 134lbs and run around 16.5psi front, 17.5 psi back. Knock on wood, I've never flatted on this bike in 6mos of riding 3-4 times a week with no shortage of rock gardens, so I haven't bothered to go tubeless.)

I am 185 In full ride gear on a full suspension,
I run tubed by choice for convenience of tire changing and simplicity.

I run a Bontrager XR-3 TLR 27.5 X 2.35 front at 25 psi. (This tire is the ONLY front tire for me for many reasons)
It comes in at 750 grams I think..

Out Back I run Schwalbe rocket ron's 27.5 X 2.25, they tip the scale at 520 ish grams and are very supple/sticky.
These get squirmy below 26 psi, I run the tire at 28.

I don't run rock gardens or get air and,,,
I never pinch

Thanks for the info folks!

I've got about $50 Jenson USA gift dollars burning a hole in my pocket, so I think I'll get a 2.4 for the front and start with that, and go from there….
They have the Ardent and the Mountain King, and a few others...