Pros & Cons of changing regular TIRES for 245/40/17 for a Hyundai Elantra 2012?

I currently have the regular original tires with 1/3 of its life. I’ve been considering buying new tires (245/40/17) or (235/40/17).
Considering Elantras are not performance cars, I would like to know what PROS AND CONS would you find with a set of tires like these?
Would I consume more gas?, or things like that…
Additional Details
I already have after market Wheels and currently have 205/40/17, I asked Les #### guys and said it would be ok

With the same aspect ratio and rim Size, the tires would be much too big in diameter. Sure they will fit ? I doubt it. If perchance they did fit, your acceleration may suffer even with the increase ratio. The drag will be more and your mileage may be less as well. I see no up side.
Stay with what you have.

The recommended 17" for your car is 215/45x17. The two sizes you mention are OK as far as diameter, but are quite a bit wider, no guarantee they won’t rub. I really doubt whether the Les guy knows, either.

I agree with @dagosa and @texases. Keep the original equipment size tires.

You really need to examine clearances with the existing tires before trading off to tires that are much wider than what you already have.

For what it’s worth, some years back I went into a local farm/ranch supply store for a couple of tires. They did not have the 195/60/15s in stock but did have some 205/60/15s in the same brand. They assured me the tires would fit according to their charts.

After paying for the tires and starting the car, I made no more than a 100 foot loop before pulling the car right back up the service doors as I could feel and hear something rubbing.
Both new tires were already gouged out on the inside edges by the strut spring perch on each side.

Point being that a measly 10 MM in width made the difference between fitting and not fitting.

If you drive in the snow the wider tires will be terrible. A car this light will climb up on top of even a light snow. Will probably hydroplane easily also.

Well you already paid to have original tires put on aftermarket wheels so you don’t seem to mind spending money. Where are original wheels? I say try the tires. You can always change them. You do not say what brand of new tires or model? They maybe awesome rain tires. Or not.

The widest tires Tire Rack shows on 17" rims in their wheel section are 215s. The sizes you mention above are about an inch wider. These rims are 2 inches larger than normal OEM and you want to add more than an inch of width. I am also concerned about rubbing the wheel wells. Go back to your dealer and ask what size is too wide. Try another coupe of tire dealers and see what they say. You might also talk to Tire Rack.

Yes, the Elantra needs 215/45R17’s.

Also, there is more differences between tires than the difference in small size changes. You will be well served to pay attention to the make and model of tire you purchase - when you return to the original size. The old tires are just plain too small and are more likely to fail - very bad.