Suggested tire size for 4.6 engine?
 

Hey guys. New to the forum as of tonight and just picked up a 05 XL with the 4.6 engine. I got it from my brother-in-law. He bought it from the company that he works for. It was his work truck. It has 246,000 miles on it but has been maintained religiously. It runs like a champ.

At any rate, I was looking to put a leveling kit on it with 35/12.50/18 but I am concerned because it has the 4.6 versus the 5.4. With the smaller displacement, would the 35" tires kill the power and fuel economy? I am thinking it might be better to go with the 33" tires. Thoughts?

Please give me your best advice guys.
Thanks
Brian

Welcome to the forum, and congrats on the truck! Great engine to have under the hood, even if is a little underpowered.

You'll definitely notice a loss of power and probably a slight drop in MPGs with 35's. However, you can offset this by simply changing your gear ratio. Most guys that have the 5.4 with 3.73 ratio will just leave it as is, but the 4.6 would probably appreciate the lower gears.

If you're 2WD, 4.30 will be good and still keep you at decent mileage with highway driving. If you want a bit more power than that and don't mind a loss of MPG on the highway, you can go with 4.56. If you're 4WD, you'll probably have to go this route since 4.30 is only available for 2WD.

Below is a picture that'll help you pick out the right gear ratio. Hope this helps!

I don't even know what gears came in this truck. What is the standard gear?

Oh wait. I assume it has the 3.73 like the 5.4

Thanks for your help.

Don't assume, CHECK!

It's an expensive oops if you ASSUME you have 3.73s when you have 3.31s.

If you look on your door tag, you'll find an axle code. This can be used to find out what ratio and differential you have. It'll either be 3.55 or 3.73 and either open or limited-slip.

I have a 2007 f150 single cab long bed 4x4 with the 4.6 with a 3 inch lift running 35X12.50X18 with stock gearing.according to my sct tuner I'm avg. 15.2 mpg. And the loss of power you do feel is so small you can hardly notice unless your trying to smoke another truck at the stoplight.it gets bogged down in the mid powerband but it can keep up with most trucks.and they can't really brag about beating a lifted truck with 35's,
You might however find a rubbing issue unless you have a bigger lift than mine.ive had all terrain ko's and the terra grapplers and they like to rub on the front valance,( the plastic piece under your front bumper) but a little trimming fixed that( maybe 1 - 2 inches off each side. And it would only happen if your backing up and you max out steering to either side. Hope this helps man. I've had it on for 20k+ and haven't had a single issue.

Thanks for that info. I was only going to put a 2.5" leveling kit on it. I don't want it far up in the air. I need to be able to trailer my 68 Camaro around.

I say stick with 33s. I just lifted my 4.6 6 inches in the air with 325 65 18= 35x13 tire and it's not as big of a dog as you'd think it'd be but I'm getting about 13 mpg on my first tank since I've gotten it back.

Anytime anyone plans on changing from stock height and tire size, they should also be budgeting to do a gear swap. That's something that's overlooked in almost all of the cases and is why there is any report of "power loss."

It's extra stress on your transmission and you won't be doing yourself any favors by avoiding it.
This isn't directed at anyone in particular, just some generalized information.