V6 vs 5.0 mileage difference

[9746Cobra]

There may not be much.

Figure the 5.0 gets it's 26 mpg with 235 tires. Put the 255's on it and it will probobly lose 1 mpg.

The v6 manual trans is rated at 29 mpg with 225 tires. Put 255's on that and it will probobly lose a point or two, as it has less torque to overcome the heavier wheels and extra rolling resistance of the wider tread. The car only weights 50-100lbs less than the 5.0.

I'm thinking real world mileage between a v6 and 5.0 stang with nice rims and tires is going to be two or three miles per gallon on the highway.

And while both can run crap gas, they both benefit from higher octanes, so call that a wash.

Agree?

 

[SID297]

It's probably only going to be a couple of mpg, but the difference will become greater with more aggressive driving.

 

[Driver72]

Well, you may be correct and may not be.

There are several factors that will affect mpg's when it comes to tires.
1. Width
2. Rolling resistance (how grippy or slippery they are)
3. Weight
4. Height

With the GT the base tires are 235/50/18 width all season radials.
The upgraded 19's are 245/45/19's but also on all season radials
The Brembo brake package are 255/40/19

I have no doubt going from the 235's to 245 you will lose a bit of mpg's, but probably only .5 mpg. They are the same tire and similiar weight.
But with the 255's from the Brembo package, you are getting a tire that's 20 mm wider than the base 235 and higher rolling resistance as it's a stickier tire.
BUT, the 255 tire is also about 3-4 lbs less in weight, so rotational mass is less. If the 255 weighed the same as the 235 I'd say yes, you're going to get 1-1.5 mpg less gas mileage. But the loss in weight should off set 1/2 of that.
So figure .5-.75 mpg less on the 255's over the 235's

I haven't looked into the V6's tires and their weights.
But keep in mind, the less power a car has, the more tires difference will affect the performance and mpg's
(ie: if the V6 mustang has only 100 hp, going from skinnier all season tires, to wider, stickier and heavier performance tires, that 100 hp has to work much harder to get those tires to turn and to keep them going down the road. It could drop a 100 hp car 3-4 mpg.
On a 500 hp car, a few extra pounds in rotational mass and 20 mm wider and stickier tires will hardly affect car at all, and you'd be lucky to drop .2-.3 mpg)

My personal mantra when it comes to tires:
I get the highest rated tires that are the lowest weight as I can get. But they have to be better than stock in performance and weight. I would never downgrade. If the top rated tire is 2-3 lbs heavier than the #2 tire, I get the #2 tire. If the #3 tire is equal to or even a pound less than the #2 tire and they cost similiar, I'll stick with the #2 tire as losing one additional pound isn't significant enough to forgo the better #2 tire.
If the #1 tire is equal to or even a pound lighter than the #2 tire, then I look at cost and other factors such as wear rating and noise, and choose between the #1 and #2 tire based on how much they are and which has a longer wear rating and the quieter on the road.

 

[Ry_Trapp0]

about a 200lb difference actually. 3.7l weighs ~3,450lbs, 5.0l weighs ~3,650lbs.