Understanding The Alcoa® Wheels Numbering System
If you’re trying to figure out how to read part numbers to spec the best wheels for your fleet or are just interested in knowing what all the digits and letters represent, this handy guide will help you do that.
It will help you understand the structure of the Alcoa® Wheels numbering system and the distinction between the three components of each part number: wheel family, polish and surface treatment.
The Part Numbering System
The Alcoa® Wheels part numbering system gives the complete information for nearly all Alcoa® wheels available.
The First Two Digits – Diameter & Width
The first five digits of an Alcoa® Wheels part number indicate the wheel family identification. The first two digits of the wheel family number are straightforward:
- Diameter
(6) – 17.5”
(7) – 19.5”
(8) – 22.5”
(9) – 24.5”
- Rim Width
(2) – 12.25”,
(3) – 13.00”,
(4) – 14”
(7) – 7.50”
(8) – 8.25”
(9) – 9.00”
The Next Three Digits of the Wheel Family
Of the next three digits in the wheel family, the fourth one is the most meaningful:
- Reserved for use by the engineering department (could include letters)
- Mounting system (most commonly a “6” for 10 on 285.75 hub pilot or a “5” for ISO 335)
- Reserved for use by the engineering department
Each wheel family is designed for specific applications and vehicle types, ensuring that you get the right wheel for your needs. It’s important to note that one wheel family typically has several part numbers.
The Sixth Digit – Polish Finish Options
Following the five digits of the wheel family is a single sixth digit, which is the polish finish identifier. Our polish options are designed to give your wheels the look you want while also offering added protection and longevity.
Polish options include:
1 Mirror polish steer/outside only
2 Mirror polish inside only
3 Mirror polish both sides
7 High Polish – both sides as applicable
8 High Polish – both sides as applicable. Reference data table for offset position.
9 Brush Finish – both sides as applicable. Reference data table for offset position.
0 Brush finish – both sides as applicable.
Final Digits – Surface Treatment
Alcoa® Wheels offers several optional surface treatments, with each one penetrating the aluminum so it won’t crack, peel or corrode like coated wheels. Surface treatments are the final two or three digits in the part numbering system, after the wheel family and polish, and include:
DB Dura-Bright® Surface Treatment
DF Dura-Flange® Wear Protection
DD Dura-Bright® + Dura-Flange® Wear Protection
BLK Dura-Black™ Wheels Surface Treatment
Part Numbering Examples – Same Family, Different Finishes
Here’s an example of a couple common 22.5″ x 8.25″ wheels that are in the same family, with the first five digits being 88565. That’s the wheel family. Using the numbers referenced above, the first digit is an 8, which corresponds to a 22.5″ diameter and the second digit is also an 8, which corresponds to an 8.25″ rim width. The third number, a 5, is reserved for engineering. The fourth number, a 6, corresponds to a 10 on 285.75 hub pilot. The fifth number is reserved for engineering.
Taking that wheel family a step further, we add on a sixth digit for polish and final digits for an optional surface treatment. Both the 885657 and 885651DB in the example below are the same wheel family, just different finishes applied to the wheel.
Taking this same wheel family example even further, let’s say you wanted the ultimate blend of durability and low maintenance, combining the Dura-Flange® + Dura-Bright® surface treatments. For example, if the wheel family still is 88565, the part number for a Dura-Flange® + Dura-Bright® finish would be:
- 885651DD – for Dura-Flange® and Dura-Bright® with Mirror Polish on the steer/outside only
- 885652DD – for Dura-Flange® and Dura-Bright® with Mirror Polish on the inside only
- 885653DD – for Dura-Flange® and Dura-Bright® with Mirror Polish on both sides
The most important thing to remember from this guide is the distinction between the three components of each part number: wheel family, polish and surface treatment, and knowing that the first two digits correspond to diameter first and then rim width. With the right information, you can quickly locate the best wheel for your needs.