Well, between poor handling on anything wet, and the droning at highway speeds, I finally bit the bullet and replaced my tires at 36k.

My ONLY regret is that I didn't do it sooner!

Running with 38lb of pressure instead of the 32 that the shop put in, I am only noticing about 1/2 to 1 mpg difference.

So, what do you get for that loss?

QUIET, smooth, grippy ride.

It was raining this morning and to be honest I didn't even feel that the road was wet. With the Eco's, whenever it rained I would take a mileage hit due to the AWD kicking in (mainly because the eco's had a lot less grab in wet weather) I didn't notice that usual mileage hit of 2-3 mpg. Additionally it stops much better and corners very well. With the Eco's in a turn I always had that "be careful of the suv rollover" feeling, but with the Tripletred's that is gone. The other thing that I noticed yesterday was that while I was driving the wind would push the body, but it stayed in the lane, with the Eco's I always felt like I was fighting it to stay in the lane on very windy days.


All told it was the best $725 spent. (Local shop with balancing, stems, and road hazzard, Tirerack wanted about that just to ship em to my house. )

 

I don't know how you drive but, either:

a) It is rather reckless with lots of wheel slippage, or
b) What you think is the "AWD kicking in" is in fact, something else
[perhaps it is as simple as rubber formulation and tread pattern - different formulations display different friction (might explain the mpg difference on dry roads), and different tread patterns move water away more efficiently (might explain mpg behavior you experience in the rain)]

I believe the FE penalty the AWD FEH pays is largely due to the added weight it carries around.

 

The FEH uses an automatic power distribution system so that if one axle starts to slip, more power is transfered to the other axle. The idea is the wheels with the best grip always get the most power with a bias towards the rear wheels. (I may be wrong on which wheels have the bias, I'm working from memory here.)

In most automatic AWD systems, there is a loss of power and thus a minor FE hit when slippage gets significant. This is part of the reason you get a bigger FE hit in the winter when driving on slushy roads than the FWD vehicles.

 

So how does that only apply when it rains?

If A) were true, then I wouldn't be averaging 32 in my MMH AWD.

If B) Were not true, what would you attribute a consistent loss of 2-3 mpg ONLY when it rains? AND the fact that it was raining today and I averaged 32 on the way to work?

Quoted from Ford:

Its not 4wd, its awd, and it activates a lot more than you think ESPECIALLY when it doesn't have decent traction. (One of the many complaints about the Conti's)

 

I actually drove my FEH with these tires (my winter treads) from the second week in December to the second week of April. With nine thousand miles on the tread, the tread depth measures between 9-10 mm on my tire gauge. I speak highly for these tires as winter tires in all conditions. I started with 37psi and in Feb. bumped the pressure up to 39 psi. These tires do not roll as well as the stock Conti EcoPlus tires, thus there is a hit with fuel efficiency. How much? Maybe as much as 1-2 mpg?

Prior to purchasing these tires, I debated with going with the Nokian WR tires which also carry the snowflake and mountain label.

 

Hmmm...I agree with you most of the way... but I would think there can be a lot of things that could account for that 2-3mpg loss other than just wheel slip, I would think humidity will have an effect on the engine efficiency just as cold air will, etc.

Why do you think its just wheel slip?

 

Here is the full description of the "4WD" system on the 05/06/07 and probably 08 MYs. Still scratching my head as to how rain causes differences in wheel speed - without some aggressive throttle - enough for the computer to decide to send torque to the rear. Ice, snow, loose rock, yeah - but rain at moderate cruising speeds, oh well, if you say so.

 

I have the AWD system and when I travel on the interstate and it starts to rain, my mpg do drop. When the rain stops and pavement drys out, the mpg increases.

 

Because it was raining today WITH the tripletreds and I didn't get the mileage hit. In the 36k prior miles it ALWAYS dropped when it was wet.

 

The Eco plus are noted for poor traction, and poor wet weather handling. So you are surprised that they slip?


Its not my job to make you understand anything, but insulting me is not called for.