What were you getting before you changed to those tires bigbluemega? I've been getting about 11/17 with the stock tires.

 

Who needs or cares about good MPH these days??

 

You have significantly changed your effective gear ratio. This will reduce your engine rpm at any given speed. You'll also find you have less torque to put down. When I went from 265s to 285s, the rpm at 80 went down from 2,020 to 1,980. I've not seen a significant drop in highway mileage. In fact, I got the best mileage ever on a recent trip (16.3).

 

Well it's a done deal- it's raining or I'd post a pic. You can definitely feel a difference but I don't think it's going to be a huge deal. I was sort of worried about gas mileage, but more worried it would break things without reinforcing the running gear. I'll just make sure the grease fittings stay well greased and the diff's get flushed regularly.

It feels like it still has enough get up and go to pull the trailer, we'll see in April I guess. So far I feel it most in the brakes-definitely effected the braking negatively. Still at 9.8 mm though so I'm not going to change to more aggressive pads or anything yet.

 

curious on the the E rating. If not towing heavy, what is the advantage of the E rated tire over the D rated tire on my Megagasser?

 

Nice tire choice, btw. I've always liked the Toyo MTs.

Are we talking CTD or Hemi here?

IF it's a CTD, you are golden just the way you are. Maybe a slight MPG loss, nothing major. You have PLENTY of low end torque to off-set the mid range gear ratio and turn those tires.

IF it's a Hemi, you will notice a difference. IMO the Hemi should only be offered with the performance superior 4.10 gears and not at all with the 3.73s. This truck is TOO heavy and the Hemi lacks the low end torque necessary to achieve proper performance. If it was me, I'd be looking at getting 4.56 gears if I was going to a tire over stock size. You'll get the vehicle up into the Hemi's power band sooner which will yield more power and better city gas mileage at the same time. Highway mileage won't suffer much (if at all) due to the fact that you have essentially TWO over-drive gears.

It won't be cheap, but you'll have a truck that feels like a whole new animal and a bit of a beast if you went to better gearing.



As far as the "D" tire vs. "E" tire thing. I've had one 3/4 ton truck in my life. A Furd diesel which I primarily used to tow my bass boat around for tournaments and the occasional wood cutting/hauling deal for my fireplace/stove insert. I bought it used with "E" tires and they were HARSH, especially when towing the 2500# or so bass boat. Because I never towed anything near capacity and almost never hauled anything anywhere near capacity of a "D" tire, I replaced them with D load range tires. Night and day ride quality difference.

I currently run a D load tire on my QC 1500, even though I have that half ton pig up to almost 7000#, it's well within a "D" tire's specs.

IMO if you don't NEED an "E" tire, don't get an "E" tire...