I recently purchased a 2011 Elantra Touring GLS that came with after market 17" wheels and 205-40-17 tires. The people at the tire store seemed concerned with putting 215-45-17 tires on the wheels even though they are standard on the ES. I am looking for a more comfortable ride and would sacrifice handling. Is this doable or is going to a 16" wheel a better option?

 

205-40-17 tires are way too small. 215-45-17 is teh correct size. If the tire place has a problem with that then thay are not a very good tire place. I'd suggest finding another or purchasing them online from Tire Rack - Your performance experts for tires and wheels or http://www.tires.com

 

Is there any difference between the SE and GLS as far as useable tire sizes?

 

No, there isn't.

 

GLS uses a 15" tire that's a little softer riding than your 17", but the ET has a naturally stiff ride.