My pivot came with Nev 2.3 in front and 2.1 rear and I have always replaced them with the same type and sizes. Thing about running a 2.3 slant 6 in the rear but I got thinking why do the manufactors run a 2.1 in the rear? Is it for less rolling resistance? I would think a wider tire would help overall performance but at a small cost of resistance. What tire sizes are you running and why.

_________________
You never know what tomorrow will bring so go ride your EBike today or walk your pooch
Fear the Yeti
"Go ride your bike today, don't let the old man in.."

Mike

2.35 Front and rear, not Nebs though.

_________________

2.3 weirwolf front

2.2 wolverine rear

In addition to the Lower rolling resistance, there is also a significant decrease in rotational weight - especially important on the rear wheel. In most trail conditions these two advantages are generally considered to outweigh the benefit of a wider tire. Smaller tires also have better clearance for when riding in muddy conditions.

On the front wheel these same advantages aren't as favorable. There's less penalty for the wider tire so it makes sense to run with one. I also think there's a small psychological advantage - having a big fat tire up front insires more confidence (at least for me it does). I wouldn't even notice having one on the rear wheel, except for the weight.

Of course your mileage may vary so try it if you can and ride with what feels best to you!

everything chadster said

plus, as mentioned front and rear different functions. why a more aggressive front? wash out the front and you're airborne, wash out the rear and its style points. why a larger front? more volume for more cush, but a minor point depending on your riding and fork. also gives a wider contact surface.

again, the tires you choose in size and aggressiveness (tread) depends on your riding style of choice. if you're going for speed, distance, time, climbing, go with the smaller, lighter tire. if your going for fun, go bigger. it's true, bigger is better. and if you'er going for a strava kom, you're off my christmas list.


note- the inside dimension of your rims may also dictate the tire range that will properly fit. a skinny xc rim will not properly fit a bigger tire, it will pinch it too much and the expected contact point and shape of the tire design will not be accomplished. this can be unsafe.

_________________
Ambition is a poor excuse for not having sense enough to be lazy. ~Milan Kundera

My 2cents:
Weight & rolling resistance, if that’s your concern then smaller is better.
If you’re more XC and ride uphill then it matters, the wider tire in front for steering.
There is no reason you cannot have both the same size except for the weight & resistance.
If every trail that you ride goes down, go wider for steering and control in the rear.
All my bikes have 2.5, and I do not climb, I shuttle!

_________________
If biking is a drug then I'm a drugie!