Adding big wheels and tires to your F150 is pretty much a rite of passage for your average 2009-2020 F150 owner, but this can become a bit of an issue if you want to avoid potential issues if you get a flat, blowout, or lost bead out there on the road or the trail. While your truck comes with a stock-sized spare under the bed and tucked against the frame, there are more than a few issues with both its quality, condition, and size that could cause you some serious headaches when you head out. The good news is that it's absolutely possible to fit a larger spare tire under your truck in place of the stock spare. The bad news is that it takes some work and throwing some cash at your truck to make it happen. I know because I tried it myself, with excellent results. Get all the details on what you need to do to get a larger spare under your truck. I managed to drop in a LT305/65R18 Falken A/T3W on an 18x9" wheel with a -12mm offset on my 2011 F150 5.0L with excellent results that gave me some extra insurance against possible disaster.

2011 F150 with Larger Spare Tire

Why you Want a Full-Size Spare

First off, why bother with a full-size spare at all? I mean, the stock one is already on my truck and will work just fine, right? Well, little Timmy, you're not technically wrong...sort of. The factory spare is fine. It's fine, just fine, and even if you do have larger tires than stock, you can still use the stock spare if you have a problem with one of your other tires. However, if you get a flat or other issue on one of your truck's rear tires, you won't be able to use the stock spare in conjunction with the other larger tire. The problem is that your differential will literally work itself to death with the difference in final drive ratio per side. This is, naturally, a BAD THING, and you'll need to take your spare tire to the front of your truck and move one of your front tires to replace the blown rear tire.

2011 F150 5.0L XL with Stock Tires

Now, having to remove two wheels and play Ring-Around-the-Rosy is pretty annoying, but not deal-breaking, but things can potentially go beyond annoying and into day-ruining when we're talking about 4WD trucks off-road. Just like with the rear differential, you can't run two different-sized tires with the front differential active. That means, your 4WD is essentially disabled by necessity of not ruining your front differential, and your truck will need to be driven in RWD until the tire can be replaced with one that matches its size. Again, in most cases, that's just annoying, however, if you're off-road and on the trail, not having 4WD can have HUGE consequences for the rest of your day, if not your safety. Being able to simply drop-on a full size spare can save you some headaches at worst, but can absolutely save your bacon off-road at best.

How to Get Clearance for A Larger Spare Tire

To get a bigger spare tire under your truck in place of the factory one, you'll need to figure out just how much bigger you're going to go. We went straight to a LT305/65R18 tire (which is equivalent to a 33.6"x12" tire), which required removing the exhaust heat shield and then figuring out what to do the factory exhaust. In theory, if you're only going with a slightly larger tire (say a 285/65R18), you may not have to do the work I had to do to fit my full-size tire and may be able to bend or modify the stock heat shield. In any case, my tire was big enough that I had clearance issues with the factory heat shield to the point where it couldn't be modified and had to be removed. However, the heat shield couldn't be removed and the larger tire dropped into place of the stock spare until something was done about the factory exhaust routing. This cascading series of problems had to be solved in order, starting with the exhaust kit.

Spare Tire Heat Shield Example

Dealing with the Stock Exhaust
Technically speaking, I already had this problem solved a while back, but it's something you'll need to consider before you drop in your full-size spare. Now, while the spare tire heat shield is your more direct problem, that heat shield is there for a reason, and it would kind of suck to melt your new full-size spare after getting it in place. So, what to do about the stock exhaust? The easiest answer is to add a dumped cat-back kit or a pre-tire side-exit cat-back, which is sort-of the route I took. I used the front inlet pipe from a Flowmaster Force II Cat-Back Kit that was totally clapped out from being installed on three different trucks and tried to fall of the truck twice, and added a Flowmaster Dumped Muffler. This setup is, honestly, obnoxiously loud, and I'm going to cut a resonator into the inlet pipe to help quiet it down soon(-ish). However, there's plenty of dumped cat-back kits on the market that can get the job done without being excessively loud like the Magnaflow Turn-Down Kits. If you want loud, you can go with the Flowmaster Outlaw Extreme and be really miserable. You could also potentially modify the stock muffler and add a dumped tip onto its end, but you'll need to do some trimming. If you want tips to exit somewhere visible, then a Pre-Tire Exit Kit will likely be your best bet, though there's too many to reasonably break down right here. In any case, once your exhaust situation is sorted, you can move on to the next step.

2011 F150 with Dumped Exhaust

Removing the Factory Heat Shield
The stock heat shield is actually extremely easy to remove, but you will need to drop the stock spare to get at it. In order to lower the stock spare, you'll need to use the factory spare tire winch to lower it. This is a little bit of process, but it's easy-peasy-lemon-squeezy assuming you have the OEM spare tire tools still handy. One of the better videos on this is from Cold Lake Ford's YouTube Channel. See below:

Once you have the spare tire lowered, it's trivially easy to get to the heat shield and its two bolts. The only thing you need to be aware of is that a lot of dust and grime tends to build up on top and within the heat shield, so make sure that when you take it off, you don't end up with a face and mouthful of dust and gravel. Ask me how I know.

2011 F150 with Bigger Spare Tire Installed

With the heat shield out of the way, you can now get your larger spare in place. Remove the stock spare from the winch bracket, struggle to roll your full-size wheel and tire combination into place, and then get your new tire on the winch. You'll likely need to remove you aftermarket wheel's center cap and center cap hardware to fit it on the winch bracket. Just make sure you store it someplace safe for use later. With the tire on the winch bracket, you can crank the winch back up and get the tire into place under your F150's bed. This may be a two-person job, especially if you're like me and have aftermarket bumper light wiring and need to guide the tire away from all that nonsense. Make sure that your new spare tire is snug under the bed, but don't turn the winch too tight, or you'll crack your wheel.

2011 F150 with Larger Spare Tire

There you have it. With a full-size spare that matches the rest of your F150's larger than stock tires, you can now take a huge weight off your shoulders and not have to worry about juggling multiple wheels or losing your 4WD when out in the bush. I know I felt a lot better before I hit the outdoors and trails in Northern Arizona, some of which you can check out here.

2011 F150 5.0L XL in the Woods

Check Out These Parts: