I know, tires...

I have been reading all I can handle and now I am blue in the face...

My delima is what tire size should I mount on my '05 Excursion with stock 16x7 wheel. I have narrowed the tires to three treads, BFG TA KO, BFG KM2, or Cooper ST Maxx. I dont know if I want to stick with the stock size, 265/75r16E, or try to find the allusive 255/85r16E. I know the 255/85r16 pushes me into the BFG KM2. However I also hear that Cooper may be adding to the production for the ST Maxx and releasing a 255/85r16. I am not in dire need for tires right now and can wait to see what Cooper does.

I dont know what to mount up on the Excursion...
- Will the 255/85 tire be a major power sink for the V10 with 3.73 gears in the axles? (This is my main concern. However, I do see many going to 285/75r16 without any powertrain changes and they seem to be happy. I dont want 285/75.)
- Do I stick with stock size, 265/75 because a replacement tire will be easier to find?
- Do I stick with stock size, 265/75 so I dont have to address/worry about the spare?
- Moving toward the 255/85 is less money to buy four when comparing 255/85 KM2 to 265/75 KM2.

I am leaning towards waiting to see if Cooper produces a 255/85r16E in the ST Maxx and have that help me make my decision. I like this size and would give it a try. However, I dont want to be real limited for a replacement if one pops and I dont want to lose to much power.

Any comments?



PS This would all be moot if I could come across a set of 2004 F250 5 spoke 18" rims with BFG TA KO 275/70r18

 

I can find them fairly often on-line, it's the $1000-1200 that makes it a non-starter for me. Heck, I'd have to put 2 locking lug-nuts on each wheel just for piece of mind. It's crazy to think those wheels and the tires would be $2k for a thief and not even have to get inside..

Sorry, can't help on tire sizes, assuming you are 2wd (or 4x4 and stay on at least dirt roads)

 

If there's anything I've learned it's that the tire size is that's best for our trucks is LT 265/75/16.This tire combination yields the best power and fuel economy.

When you start playing with tire size, you develop an expensive gambling habit that you never get over until you're happy. I've gone up on tire size on the '01 Excursion due to the lift and noticed my mileage went from 18.6 mpg to 15-maybe 16 mpg. (17 mpg all highway driving)

Given that you have a V10 and finding tires is much easier, I'd stick with the BFG All terrain 265s. They come in a load range E, are easy to find, and you definitely can't go wrong with the traction. I've run about 6 sets of BFGs and I can tell you that they hang on to the road and whatever you throw at them well.

 

The MPG issue with changing tire sizes is very mirky..
The only true way would be to use GPS to calculate distance traveled, or go from point A to point B and compare fuel consumed between tire sizes.

Via the ODB2 port, mph matches GPS's mph. Of course, the dash speedo is 3 mph OVER at 72 mph. with 265/75/16 - and I believe the overhead display which is driven by the PCM is going to be the less inaccurate.

Folks who have gone to 285/75/16 report the speedometer is dead on now, but of course the ODB2 info is now off and thus the overhead display is even worse. Then add the fact that the odometer (distance traveled) is wrong with larger tires (you go farther than it says, but you also went FASTER thus more air resistance) so it'll make the mpg calculations worse (even hand calculated).

 

My Ex is a bone stock XLT 4x4 and I do not have a overhead console. My MPGs are all calculated by hand from the odometer reading and gas receipts. MPGs are not a big concern because she sits 90% percent of the time.

That being said it does seem that sticking to 265/75 would be the smartest option and it would keep the "modification" can of worms closed for now. IDK...

 

I think the trick is to get the newer 17 or 18" wheels and narrow tires for those instead of the huge tires for the 16" wheels.

 

I just don't think I could recommend a smaller width on the Ex. A narrower tire with a taller sidewall is not going to change your handling characteristics in a positive manner. It's a small amount but it all adds up.

Tire width:
255 mm = 10.04"
265 mm = 10.41"
285 mm = 11.22.

The sidewall height will be the following:

255/85 is 85% of 255 = 216.75 mm = 8.53"
265/75 is 75% of 265 = 198.75 mm = 7.82"
285/75 is 75% of 285 = 213.75 mm = 8.41"

These are all rough examples as each tire manufacturer measures their tires a slightly different way. You can pull up actual specs of each tire on their web sites to give you an idea of a specific tires width (overall width and tread width - 2 different measurements). The width numbers above will be overall width and not tread width.

Looking at one my tire distributors - the 255/85 comes in a BFG Mud Terrain 10 ply E rated and an E rated Toyo Open Country M/T. There are definitely others out there - just happens to be the ones I could easily search on and are currently available and in stock.

Is there any reason you want to go with a narrower tire?

 

I want taller w/out the price tag. I have the bfg km2 on my mind and the 255/85r16 is less expensive to buy vs the 265/75 and 285/75. Plus to go taller with the factory 16x7 wheel, then the 255/85 is the ticket.

I am try to balance wants and needs...I need to buy new tires and I want to get the most for my money.

 

I have been running 285 75 16s for about 100,000 miles on my stock wheels. The first set lasted 81,000 miles with no issues, just keeping up on rotating and balancing. I would think the oddball size would be more expensive. That said, the cheapest route would be the 265s, but it all depends on how bad you want a taller tire.

 

I wouldn't get too deep into it, just go buy some tires. Also; I believe in what Toreador said, unless you want to mess up the best power and MPG the factory spent millions determining.