Tires: tire size for Dodge Ram 1500 w/Hemi, poor fuel economy, dodge ram 1500

Question
I have a 2007 Dodge Ram 1500 with a Hemi. Currently, it has 275s and 20 inch tires. My dad says that if I move down to 16 inch tires, I'll get much better gas mileage. I assume this is true. However, I need to know if there are any other concerns I should have regarding reliability of the truck if I change from the factory established tire sizes. Is there any reason I shouldn't make this change?

Thank you so much for your help!

Jennifer

Answer
Jennifer,

First, your dad is wrong.  You need to go larger in size to get better fuel economy - but the affect is small.  Here's a more detailed explanation:

http://www.barrystiretech.com/rrandfe.html

http://www.barrystiretech.com/rrandfe2.html

Sorry, but I'm a dad, too - and while I would hate to disappoint my daughter, I do indeed make mistakes!

What DOES have a major affect is the tire itself.  You need to pick tires that are good for fuel economy - and that means you have to sacrifice treadwear and/or traction.  Tire Rack has indicated which tires have better fuel economy - based on what the tire manufacturer tells them.  So it is only somewhat reliable.

In your case, you can be sure that tires with high treadwear ratings will have poor fuel economy, and the same can be said of tires with high traction.  It's a matter of picking the right tire.