Have rims that can take a 1.75 tire. Can they take larger?

[Singleton]

I'm pretty sure I could safely force going up a tire size, but what about two sizes?

Is there an advantage in doing this, assuming everything works?

Looking to make the best use of limited funds and I have been told tires make the most difference.

 

[Karate Chicken Industries]

Just take care in setting the bead if you size the tire up from the rim. My 1940 Schwinn BMX has 2.5" tires on skinny XC MTB rims and they run well.

The only advantage in tire to rim size is running a skinnier tire on a wider rim. For some Physics reasoning they tend to roll faster, according to some Streamliner afficionados.

 

[Singleton]

So what advantages are there to fatter tires?

 

[Wildcat]

They look better and have a better ride I think. Smooth tread will be just as fast as 1.75 tires, or better if they are higher pressure tires.
One thing to also consider is the fitment to your bike, clearance of the frame and fenders if you have them. I would switch to 2.125 because there is a lot of variety; you should be able to find a pair for a decent price. I just picked up a few sets of wide tires after waiting for them to go on sale.

 

[BartRidesEternal]

So what advantages are there to fatter tires?

Float like a boat:

My experiences so far:
My Klunker bike (picture above) has narrow rims (Staystrong BMX) and 3 inch or 75mm wide tires (Felt Berm Master).
For me, riding over hard roots and stumps on singletracks, there is no need for suspension, just let a little air out. So comfort for one.
Interesting side observation: Due to the tire wall flexing easier, when going the limit in corners, the bike feels like its drifting a bit.

I do believe that very fat tires have a bit more resistance.

Not the best example due to the difference of the bikes and tires:
Commuting to work:

• Riding with 28x1.75 tires I managed an average of 32km/h (19,88 mph)
• Riding with 28x2.6 I manage an average of 26km/h (16,55 mph)
• With the FATbike 26x4.0 I managed an average of 23km/h (14,29 mph)

Again, not the best example.

I do like the look of fatter tires which gives me more motivation to ride

In the end it depends

 

[Karate Chicken Industries]

So what advantages are there to fatter tires?

Like the others have said, more cushion for the pedal pushin.

 

[nevin]

1.75 & 2.125 are interchangeable. (anything wider... not sure, no experience)

but back in my BMX days, i ALWAYS preferred 1.75 over 2.125
to me, the fatter tires always felt sloppy, even when properly inflated. but 25+ years later my opinions might have changed.... or my intent changed....