Tire and rim weights

[aerohead]

Originally Posted by 2009Toyotoad

Just an observation My 15" by 5.5" steelies with hubcaps were nearly 6 lbs heavier per wheel than the Sparco Alloys I replaced them with ,sized 15" by 6" . I run 65 series LRR Goodyear fuel Max on both sets of wheels and did see a slight MPG improvement but I didn't track the improvement over the long term. The car handles much better on the wider wheel. Also as most of my daily drive is 65 MPH or better at times. I would not want to chance running on donuts. There is simply not enough tread to maintain traction in an accident avoidance situation.

I'm unsure if I can put my hands on it,but somewhere in my rat's nest is an article CAR and DRIVER did in the 90s.They took a Corvette and replaced all four wheels with space saver spares and ran it on the skidpad at Chrysler's proving grounds.The lateral G-forces were quite close to that of the OEM tires.
These would have been the actual space saver tires,not another tire on the rim,but it was interesting.

[ME_Andy]

A wider tire deflects less as it rolls, which also requires energy. So I'm not too surprised that wider tires don't hurt mpg. Saw a chart for this online once. You will never see me running 4 spares. Lol

[BabyDiesel]

I will say that the 4" wide space saver rims did not affect handling in a measurable level. I took turns just as fast as I always have and the car stuck.

I couldn't imagine the rolling resistance impact from running the bias ply skinnies! The space saver wheels hurt rolling resistance bad enough with mt radials.