In 2010, I purchased an almost brand new Kia Soul ! that had one previous owner. That person had replaced the factory rims / tires with 18" Alloy rims with 40" low-profile tires. At the time, I averaged 26 MPG which, while not amazing, wasn’t bad enough to concern me. Almost every person I spoke with said I could probably chalk it up to the low-profile tires. This year, when I needed to replace my front tires, I opted to replace all four so that I could go back to the 45" factory size. The tire salesman assured me that the ride would be much better and that the MPG would not be affected, and would actually improve (albeit, marginally) since it was the intended tire size.
However, since replacing my tires, I have actually experienced lower MPG than I had before. At the moment, I am averaging 24 MPG. Now, I know that may not seem like a lot, but it ends up being a loss of a full gallon of gas or more each time I fill up. I have been religious about keeping the tires at the recommended setting (33 PSI). I check the pressure each time I fill up the tank and log it, along with my mileage. I change my breaks, oil, plus and filters like clockwork and I drive like a grandma! I rarely drive over 65 / 70 MPG and when I accelerate, I make sure that I do it slowly and smoothly so that the “Eco” light stays on, but nothing has improved. I have an app that I have used to calculate the mileage per gallon for the last six months (before the tire change and after), and I’ve even gone back to manually check their numbers to make sure there wasn’t a fluke in the programming that was rendering incorrect totals. Nothing!
I’m at a loss and have no idea where to start solving this riddle, but it’s annoying me to no end. I feel like I’ve been duped into spending more money than I intended to when I replaced my tires. Has anyone had this experience or know of any issues that may cause this drop in MPG? I’m a total car novice and don’t really have anyone in my life who can help me with these things, so please be kind.