If you're tired of rubbing your sidewalls, installing a 1966 mustang mini tub kit is basically the only way to get those massive rear tires under your classic Ford without cutting up the exterior quarter panels. Let's be honest, the original wheel wells on a '66 are pretty cramped. Back in the sixties, nobody was thinking about stuffing a 315-series tire under there. They were happy with skinny little bias-ply tires that looked more like something you'd find on a bicycle today. But if you're building a Pro-Touring machine or a serious street-strip car, those "pizza cutters" just aren't going to cut it.
The beauty of a mini tub is that it lets you keep the stock exterior lines of the car. You don't have to go full "dragster" with massive flared fenders that ruin the iconic silhouette of the Mustang. Instead, you're moving the inner wheel house inward toward the frame. It's a subtle change from the outside, but it makes a world of difference when you're looking at the car from the rear and see that meaty stance.
Why You're Probably Considering This
Most guys start looking for a 1966 mustang mini tub kit once they realize they've hit a wall with their current setup. Maybe you bought a nice set of 17x8 wheels and realized that even with the perfect backspacing, you're still millimetres away from the fender lip. Or maybe you're pushing some serious horsepower through a crate engine and you're just spinning the tires through the first three gears.
Traction is the name of the game. A mini tub allows you to jump from a modest 245 or 255 tire up to something like a 295 or even a 315, depending on your suspension setup. That extra contact patch is what actually puts the power to the pavement. Plus, let's face it—it just looks cool. There's something about a vintage Mustang with a wide stance that screams performance without trying too hard.
What's Actually in the Box?
When you order a 1966 mustang mini tub kit, you aren't just getting a couple of pieces of sheet metal. Well, you are, but they're specifically engineered pieces. Most kits come with widened inner wheel houses that are designed to follow the factory contours of the trunk and interior.
You'll usually find: * Two enlarged inner wheel wells (the "tubs"). * Template pieces for cutting the floor and frame. * Reinforcement plates (because you're cutting into the structure). * Sometimes, relocation brackets for your shocks or springs.
It's important to remember that the tub itself is only half the battle. Since you're moving the inner wall inward, you're going to run into the factory leaf spring location. This is where things get interesting and where you really have to plan out your build.
The Reality of the Installation
I won't sugarcoat it: installing a 1966 mustang mini tub kit is a big job. It's not a "bolt-on" Saturday morning project. You're going to be doing a lot of measuring, cutting, and welding. If you aren't comfortable with a plasma cutter or a MIG welder, this might be the time to call in a professional or at least a friend who knows their way around a fabrication shop.
You have to strip out the interior, pull the rear glass (to be safe from sparks), and basically gut the back half of the car. You'll be cutting out the factory inner wheel houses and a portion of the trunk floor. Some kits even require you to notch the rear frame rails. It sounds scary, but if you follow the templates and take your time, it's a very manageable process for a seasoned hobbyist. The goal is to make it look like the factory should have built it that way.
Dealing with the Suspension Bottleneck
Here's the thing many people forget: a 1966 mustang mini tub kit gives you the room for the tire, but your leaf springs might still be in the way. On a stock '66, the leaf springs sit right where you want that extra tire width to go.
Usually, you have two choices here. You can use a leaf spring relocation kit, which moves the springs inward to align with the new tubs. This is the more budget-friendly route. However, a lot of guys take this opportunity to ditch the leaf springs entirely and go with a 4-link or a torque arm suspension. If you're already cutting the floor for tubs, it's the perfect time to upgrade the whole rear geometry. It makes the car handle like a modern sports car rather than a 60-year-old leaf-spring cruiser.
Maintaining the Interior Look
One of the biggest concerns for Mustang owners is the back seat. Since you're widening the wheel wells, the rear seat bench isn't going to fit anymore—at least not without some surgery. If you're building a dedicated track car, you probably don't care. You'll just throw some carpet over the tubs and call it a day.
But if you want to keep that "factory" feel, you'll need to have the rear seat frame narrowed. A good upholstery shop can trim the wire frame of the seat and reshape the foam so it fits perfectly between the new, wider tubs. When it's done right, most people won't even notice the seat is narrower. It keeps the car functional for the family while still hiding that massive rubber underneath.
Wheel and Tire Selection
Once the 1966 mustang mini tub kit is welded in and painted, the fun part starts: picking the wheels. This is where you have to be precise. You can't just guess on backspacing anymore. You'll want to use a wheel fitment tool to measure exactly how much room you have from the new inner tub to the outer fender lip.
Common setups after a mini tub include 18x10 or even 18x11 wheels. Pairing those with a 295/35R18 tire is a popular choice because it offers a great balance of grip and aesthetics. If you've notched the frame and gone with a narrow 4-link, you might even squeeze a 315 back there. Just remember that the wider you go, the more "dialed in" your alignment and axle centering need to be. There's no room for "close enough" when you're running tolerances that tight.
Is it Worth the Effort?
You might be wondering if all this cutting and welding is really worth it just for a couple of inches of tire. For most enthusiasts, the answer is a resounding yes. The transformation in how the car drives is massive. You get better lateral grip in the corners, way more confidence on the highway, and the ability to actually use the power your engine is making.
Beyond the performance, a 1966 mustang mini tub kit adds a level of "pro" quality to your build. It shows that you didn't just throw parts at the car—you actually engineered it to be better. It's one of those modifications that separates a standard restoration from a high-end custom build.
Final Thoughts Before You Start
Before you go out and buy your 1966 mustang mini tub kit, just make sure you have a clear plan. Decide on your suspension first, because that will dictate which kit you need and how much cutting is required. Also, make sure your rear axle is the right width. Sometimes people find it easier to use a slightly narrowed 9-inch rear end in conjunction with the mini tubs to get the deep-dish wheel look they're after.
It's a project that requires patience and a bit of "measure twice, cut once" philosophy. But once you're cruising down the road with that aggressive stance and the tires are hooked up tight, you'll forget all about the hours spent under the welding mask. It's one of the best upgrades you can do to a '66 Mustang if you're serious about performance.