With the prices of drag wheels on the upwards of $600+ dollars and if you plan to drag your Mustang for the optimum ET’s then a special purpose set of wheels and tires are needed. A cheaper alternative is to use factory aluminum 15"x4" spare wheels with your drag tires. This article is designed to guide you thru the process, to show you what works and what doesn't.
There are two main differences between the 89-90 GT aluminum spares and turbo coupe spares. The turbo coupe spares use T125-70/15 tires, whereas the GT spares are T125-90/15. (NOTE: Only the GT spare on the left in the picture below has the temporary spare tire on it.) This makes the tires much larger on the GT spares vs. the turbo coupe spares. The other difference is the curvature of the rim to clear the front brakes. The turbo coupe spares will not clear the front 11" late model Mustang brake calipers. But we solve that issue latter.
Check out the picture above. The wheel on the left is the 89-90 GT spare, the one on the right is the turbo coupe spare. Look at the center where the wheel mounts to the car. The GT rim dishes in deeper than the turbo coupe wheel. This is how you can tell them apart.
How to Use:
Spacers can be made to make the turbo coupe wheels clear the brakes. Mag wheel lugs were used so I wouldn’t have to replace my existing wheel studs.
With the drawings above a machinist should be able to fabricate the wheel spacers that are needed. The lugs are common off the shelf items at any auto parts store (same lugs as used on Centerlines). The only other operation needed is to open the holes in the aluminum spare wheels to 23/32" also. I did this on my drill press at home, line up on the existing holes provided by Ford.
On the front go with a P165-70/15 radial. I bought mine from Wells Performance in Florida for about $100, this included shipping all the way to Louisville. On the back use a 26"x9" drag radial. I use Mickey Thompson Sportsman G60x15 because I was able to get them for free used. By using DOT tires both front and rear you can drive the car to and from the strip.
When the above rims and tires are mated with a set of centerline rear wheels then the combination doesn’t look too bad. If you really want to be cheap go with a set of 10 holes and the above tires.
The Bottom Line:
I have about $300 invested in my whole setup. In the process I lost about ____ lbs. over my typical daily driver wheel / tire combo and my car went from running a best of 9.13 in the 1/8th to 8.73 seconds. My 60-foot times went from 2.12 to 1.97 seconds. I can now leave the line @ 2,200 rpm instead of feathering the throttle as before. If I was running true slicks then I could launch even harder and my times would even drop more. If you are a beginning racer out there then note that slicks are one of the best investments you can make. Slicks will drastically lower your ETs and make the car easier to drive at the strip.