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ElantraClub - For Elantra Owners and Enthusiasts _ i30 Based General _ Looking for input

Posted by: Alex2013GT Nov 5 2014, 12:07 AM

So I've had the GT for over 2 years and have put about 40k miles on her thus far. When I first got her it was rare to ever get a tank under 30 MPG's and when I mixed in a long highway trip it was more in the mid 30's and even got in the upper 30's occasionally.

So earlier this year I decided to switch out the stock wheels and tires after hitting a pot hole (http://www.elantraclub.com/forum/index.php?showtopic=36365&hl=konig). I put on 17x7.5" Konig Crown wheels and 225/45/17 Kumho Ecsta 4X tires. I've been very happy with the increased performance and looks, but ran into a somewhat unexpected result. My fuel efficiency has dropped considerably.

With slightly wider wheels and stickier tires I guess I expected a slight drop, but the wheels are lighter so I assumed there wouldn't be too much. Well, on my normal commute my average has dropped to 27-28MPG's. On longer highway trips I barely get over 30 MPG's now.

So is it the slightly wider tires combined with a stickier tread that is giving me a good 15% drop in fuel efficiency? Does that sound reasonable? I still love the wheels and tires, but am just surprised at the considerable drop I am noticing.

As an FYI, my commute/driving habits haven't changed and I've given it an extended period to make sure my sample size wasn't too small. At this point, looks like it is what it is, but just curious to get others input.

I've also taken a few trips up to PA both before switching and after switching the wheels. Before I got about 36 MPG, and after I couldn't even get 30 MPG's on some tanks.

Posted by: elantragt Nov 5 2014, 06:00 AM

It's possible the tires (stickier, less rolling resistance) are part of the drop. Those tires do have a slightly larger diameter (+.35") than stock so your speedometer will read slightly lower than stock. Are you using the trip computer to calculate MPG numbers?

Have you tried pumping a little more air in the tires? Colder weather/winter gas blend can lower your numbers.

Last but not least, cars I've owned seem to get lower MPG as they age ... could just be me, though.

Posted by: VIG Nov 5 2014, 07:58 AM

I've noticed this in the Mustang also. Once I put the 255s all the way around my mpg dropped from mid 20's to high teens.

Posted by: Bobzilla Nov 5 2014, 09:44 AM

I ran into the same issue with the 4X. That and they chop and destroy themselves in about 30k miles. I went from the OE 215/45/17 GY RS-A's to the 225/45/17 4X. They were great for about 15k miles but the mileage was definitely lower. After that, they got louder and louder. At 34k miles they were at 2-3/32's of tread and were deafening.

Recently swiched to the PA31's in 205/50/17, they're REALLY quiet, much better in the rain (and hopefully snow, the 4X were horrific at best) and I picked up the 1-2mpg I'd lost.

Posted by: Alex2013GT Nov 5 2014, 02:41 PM

Ahh I'll be curious to see how long these last then. Unfortunately I didn't have as much time to do research as I would've liked since I needed to replace the flat tire ASAP. So maybe once I replace these I'll pick back up some of what I lost which which would be nice!

Mitch, yes I did start keeping the tires at a higher PSI which has helped a little (currently at 35 PSI). And these are all hand calculated numbers.

This has been something on my mind for a while, just finally got around to posting about it. Next time I purchase tires I will definitely be checking in here first and doing some more detailed research.

Posted by: Bobzilla Nov 5 2014, 02:44 PM

The best wear/economy I got with the Forte (2880lbs) was 37 frt, 36 rear. Anything over that was starting to wear the centers too much.