ruley73

I entered the correct info listed below into this calculator. According to this the engine should be running at 2104 RPM at 65MPH and 2427 RPM at 75 MPH if you have 16 inch wheels with OE size 235/65/16 tires. If you have 17 inch wheels with OE size 245/65/17 tires the engine should be running at 1997 RPM at 65 MPH and 2304 RPM at 75 MPH.

This is consistent with what I observe when driving our 2007 Equinox with 16 inch wheels.

Fifth gear ratio is 1:1
Final gear ratio is 2.7:1
235/65/16 tire height is 28.03 inches or 712mm
245/65/17 tire height is 29.54 inches or 750mm

Garry Bunn Jr.

I just dont understand this thing. I have a 2004 dodge Durango that was about 5000 lbs and it gets better gas mileage than my 06 equinox. It's only getting about 14 mpg. My durango gets 16.7 mpg. Its crazy.

ruley73

I find this very hard to believe, especially if said Durango has a V8. The worst fuel economy I've ever seen with our Equinox was 15 MPG with all city miles and a heavy right foot in the winter. Usually, it's somewhere between 16-17 MPG city and 21-23 MPG highway. I always manually calculate the mileage. The cluster is never 100% accurate. If the tires are different than the original size you need to factor that into your calculations as well.

Garry Bunn Jr.

It has brand new original size tires all the way around. Mine does not have the cluster. I've had it for 3 weeks and the mileage is improving. First week I got 220 miles on a tank. Second week 240 miles. Had to fill it up today and this time I got 270 miles out of it. That puts it around 16 mpg which is an improvement. So that sounds much better. Fixing to give it new plugs and wires. Any recommendations on which ones would be best?

ruley73

Use OEM AC Delco Iridium spark plugs and a decent set of plug wires. As long as you don't use cheapest wireset you'll be fine. When I changed my spark plug wires years ago, I used Denso brand that I ordered from RockAuto.