Alfa Romeo 2600 Wheel and Tire Talk

Perhaps, like me, you figure if you didn't have to worry about wearing out those old Michelins or Pirellis you would start driving your car like you know you really want to and more often. The answer to these questions can only be answered by providing one with the alternatives. Right now, it may be easier to address the issue than it was ten or fifteen years ago because many new cars are using 16, 17 and even larger diameter wheels which would have a better chance at fitting over 2600 brake components. If you want to stick with stock tires, they are still available through Coker Tires in USA. Expect to pay plenty, but if you don't drive your car much, they should last you for a long time. If you want to go with a different wheel, you still may want to get a complete set now to squirrel away for concourse and show activities.

I have called Coker tire recently. As of April 5, 2001, the price for the 165/400 Michellin tire was $155.00 and the 185/400 tires were $191.00. Do 185/400 tires fit on our wheels? If it ever becomes possible to convert to a 16 inch rim, original type 185/16 Michellins are also available for $191.00. Tubes are the same for all these sizes and cost $24.95 each. (Going stock is looking better all the time.)

If you want to buy different wheels and tires, you will have to find something that will fit inside the wheel wells. The front wheel wells are not really a problem, but the rear wheel wells are very narrow, about 215mm (8 1/2") for the Sprint. The hub where the wheels bolt on are about dead center in the opening which translates to a zero offset wheel. The bolt pattern for the wheel is 5 on 4 1/2". This is perhaps the only good part of the equation because the bolt pattern is very common. The zero offset is a challange because most new cars of a positive offset of about 40mm or more. This simply means that the center part of the wheel where the bolts go through is 40mm out toward the wheel face from the center point of the total wheel width. It should be noted that the use of aftermarket wheel spacers of any kind can be dangerous and I strongly suggest you avoiding using them, especially anything wider than half an inch or 10mm.

Alfa 2600 brake drums and disks are huge, so it is not easy to find a wheel that will fit over these components. While 16 inch wheels are larger than 400 mm wheels, the drop on a steel wheel and many alloy wheels (the part of the rim that is welded on to the center) is actually smaller in diameter than the drop on our 400 mm wheels. 16 inch wheels are often only available in 7 inch or greater widths. The original wheels are less than 5 inches. While 6 or 6 1/2 inch wheels would be ideal and 7 inch wheels might fit, one would have to pay special attention to make sure the offset is zero and also make sure that there is no side to side slop in the rear suspension. Keep in mind that wheel widths are measured from the inside of the rim where the tire seats against the metal (called the bead). This means that when one takes into account the thickness of the metal and the flare of the rim where the weights are attached, a 7 inch wheel is actually closer to 8 inches in overall width. Now here is where it gets to be a real challenge; the newer speed rated tires are usually low profile having a sidewall height of 65 percent or less of the tread width. In order to maintain the tire diameter and final drive ratio, one must find the largest possible tire width without rubbing the wheel wells. Add to this the fact that most of our old cars have worn rear suspension bushings which further increases the chances for clearance problems. For your convenience and tinkering pleasure, I have included a handy tire sizing calculator. (requires java script enabled browser)

Using the tire sizing calculator, it can be determined that a suitible tire size would be a 205/65 16" or a 205/60 17" would be a closer choice. Still, at just over 8 inches wide, that wouldn't leave much room for slop. After calling around, it appears that no one makes a 205/65 16" and 205/60 17" doesn't appear to be available either. 205/60 16" is a common size, but will result in loosing nearly an inch in diameter. Try checking out online tire sources, but make sure to pay attention to the actual tire cross section widths. Also pay attention to tire speed ratings:

U=124 MPH, 200km/h
H=130 MPH, 210km/h
V=149 MPH, 240km/h
W=168 MPH, 270km/h
Y=186 MPH, 300km/h (wouldn't that be exciting?)
Z=149 MPH, 240km/h and over

Let's look at the 205/60 tire. The first number (205) is the section width of the tire measured in millimeters and it should not be confused with the "tread width". Tread width is the actual rubber on the road -- section width (the like our "205" in millimeters) is the widest part of the tire, which is most often the bulge in the middle of the tire. Section width is as stated, but tread width can change significantly from manufacturer to manufacturer. The second number "60" is the sidewall height measured as a percentage of the tread width. So you see most tires are expressed in metric, imperial, and percentage units. Talk about confusing; it is no wonder that that space probe crashed into Mars.

Warning: Never mount a tire on a rim width that is not approved. Wheels narrower or wider than approved will stress the tire sufficiently to cause poor service and may even cause tire failure.

So what is my plan? I have found a local wheel manufacturer who can cut the center out of my wheels and weld them onto a 16" rim. The problem is that none of the wheel rim manufacturers make a 16 inch rim that matches the center of our 400mm wheels. If there were enough interested people, correct rims could be produced at a metal spinning company, but it wouldn't be cheap. This solution would preserve the beauty of the original wheels but allow the use of a standard 16 inch tire. More on this as progress is made. I still want to make sure that the rim clears the brake calipers. I am currently running with a set of generic 15" steel wheels and 185/65 tire but they are much too small and funny looking. Check out my car at Portland International Raceway. My car is a rear disk brake and fitting these wheels required grinding some fat off the outer part of the brake caliper (hardly a recommended proceedure). Other 2600 owners have come up with other solutions and I am eager to post them on this page. If you have more info or personal experiences on this subject, please feel free to share it with me and I can post it here for all to see. . . . click here to submit your idea
maifor many communications options. Happy motoring.
Your friend Robert Piacentini in Portland Oregon.

Technical disclamer: Anything you do to your car which is not considered stock is at your own risk regardless of what you have read here. The information is presented here is only a decision making guide. Installing the wrong sized wheels or tires on a car could possibly result in tire, wheel, or brake failure and could cause injury or death to the occupants of the vehicle or those in other vehicles. Try to use common sense and if you don't know what you are doing, then don't do it.

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