I have stock tires on 09 Base Fit,(Dunlop 31 a/s, size 175/65/15). If I replace with 16" x 7 wheels and 205/50/16 General uhp summer tires will they affect acceleration and mpg noticable. I cannot afford acceleration much worse than it already is, but as I'm getting 34 mpg would prefer lower mpg in exchange for better handling, which is truly awful, and I have yet to drive it on a wet road! I cannot find a better tire in the stock 15" size with a profile that would not change my gearing, so am looking to go one size up to 16" and lower profile.

 

Use this link to help calculate the tire size differences
Wheel-Tire size comparer - RIMS-N-TIRES

As for accell and MPG, weight will be a factor. As will rotational size (is this the correct term.)

 

Assuming the wheels weigh the same your acceleration will be marginally slower since you have more tire touching the ground the engine has to work harder.

Although if you go to a wheel that is drastically lighter than the stock one then your acceleration, mpg, handling, and braking will all increase a good amount.

 

Maybe you should get 205/45 tires instead. Those will be closer to stock diameter.

Regarding the acceleration/fuel efficiency penalty, it also depends how much your new larger wheel + lower-profile tire combo weighs vs. stock. Mine went +6 lbs per corner, so no surprises there - I got marginally worse acceleration and fuel economy. Unfortunately not many places show you how heavy the tire is.

 

Tire Rack sometimes has weights on some of the tires they carry. Most of them, but not all of them.

 

Tire Rack huh? That's good...better than going in blind, so to speak

Toyo is another manufacturer that carries tire weights on its website.
www.toyotires.com

 

I changed my stock tires from the Bridgestone 185/55/R16 to Goodyear Assurance FuelMax 205/50/R16 for increased mpg.

It did actually go up about 2 mpg.

I think these tires are heavier. I kept the stock wheels. I was considering lighter 16" wheels but can't afford it. That would have helped a little.

For these slightly heavier, bigger tires I don't notice an acceleration loss. If there is any, I can't tell. I don't drive spiritedly, just for mpg.

 

I was just going to recommend these, as yeah, looks like from reading tests they could get you a 1 &1/2-2 mpg gain.

Was looking at these on TR the other night, I believe the Fuel Max 205/50 is like 19 lbs
(stock Dunlops are 18 I believe, so NOT an issue)

Also Michelin has Energy Saver tires out soon (been on sale in Europe for a year and a half)

more info here https://www.fitfreak.net/forums/eco-...l-economy.html

 

Acceleration and mpg will be a little worse due to the extra weight and bigger diameter of the tire. The further the weight is from the hub the harder (more torque) it takes to turn the wheels.
Suggest you consider 205/45x16 tires as the diameter is a little smaller (23.26 vs 23.92) so the lesser radius makes up for the extra weight. You will have a 1.7 mph error at 60, reads 61.7 mph at true 60, and a 28 mile higher odo reading per thousand miles. Not significant.