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You are nearing the end of your Big Bolt project and want to get it on the road. But your tires have too many dry rot cracks and not enough tread. Maybe you don't want the bias ply, tubed tires anyway and want to upgrade to a tubeless radial. Many of us "Big Bolt" owners have wondered what modern (i.e., tubeless) wheels will fit our trucks. Here's Grigg with some info on how to find...
| By Grigg Mullen III Bolter # 6590 1948 Chevy 2-Ton 5-Window |
01 March 2008 |
Note: This is the first installment of an article that will eventually cover all the medium duty trucks (1.5-ton & 2-ton conventional and COE), 'late '30's through '73. For starters, we're covering 3/4-ton through 2-ton AD trucks.
Nomenclature used in this article
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DANGER -- Wheels split in the very middle should be avoided! -- DANGER Don’t even try to put air in one that is low! |
| Overview |
When we get an antique truck to restore or drive as is, almost invariably it will need to have its tires replaced as the tires found on most restoration "projects" are not only worn but dry rotted and cracked as well. We have two options: staying original and just replacing the original style tubed tires (assuming the wheels are still serviceable); or upgrading to modern tubeless tires and single piece wheels. We will focus on the available newer wheels and tubeless tires.
Most of the information I have is about the 10-lug wheels used on our AD (Advanced Design 1948-1954) trucks. Much of what I have learned comes from experience with AD trucks and reading the Accuride Wheel Catalog. Of particular interest is page 28 with the 10 lug on 7.25" circle and 5.25" center hole. This is the exact bolt pattern used on late AD 1.5 and 2 ton trucks. Earlier trucks have the same bolt pattern but a smaller 4.75” center hole, because of this the new Accuride wheels are not a direct replacement for trucks with this smaller hub diameter, we’ll get to the details and solutions later.
As a side note, Ford used the same bolt pattern with a larger 5.46" center hole on the F-Super Duty trucks from 88-97, available in a 16" rim. Because of the larger center hole these wheels are not directly useable on our Chevy trucks without bushings in the center holes, as the wheels are hub-piloted and it is important that the center hole fit snugly on the hub. Also different are the Ford wheels/hubs use 9/16” studs, while our AD Chevy trucks use 5/8” studs.
| Original Equipment |
The first thing to do when searching up more modern wheels for your truck is to know what you need. Knowing your lug pattern, center hole diameter, etc is critical in finding wheels to fit your truck. Here is some info on the factory set up. Given that our trucks have often led hard lives and weren't always maintained according to factory spec, it's always a good idea to check if your wheels and tires are even the correct ones for your truck! There's no telling, sometimes, what might have happened 40 years ago in the middle of a corn field to keep the truck rolling...
| '47-'53* "Advance Design" Trucks | |||||
Truck size |
Wheels |
Lugs |
Lug Pattern |
Center Hole |
Tires |
3/4-Ton (3600) |
17x5.0 |
8 |
6.5" Circle |
7.50-17 |
|
1-Ton (SRW)(3800) |
17x5.0 |
8 |
6.5" Circle |
7.50-17 |
|
1-Ton (DRW)(3800) |
18x5.0 |
8 |
6.5" Circle |
4.56" |
7.00-18 |
18x5.0 |
8 |
6.5" Circle |
4.56" |
7.50-18 |
|
1.5-Ton (4400) |
20x5.0 |
10 |
7.25" Circle |
4.75" |
7.00 - 20 |
20x5.00S |
10 |
7.25" Circle |
4.75" |
7.50 - 20 |
|
| 2-Ton(COE & 6400) | 20x6.0 |
10 |
7.25" Circle |
4.75" |
7.50-20 |
20x6.0 |
10 |
7.25" Circle |
4.75" |
8.25-20 |
|
20x6.00T |
10 |
7.25" Circle |
4.75" |
9.00-20 |
|
* Post 1953: In 1954 the 10-lug center hole diameter increased to 5.25" In mid 1955, GM switched the stock wheel from a multi-piece tubed tire to a single piece tubeless for the '56 model year. The tubed tires (and their wheels) were still offered as an option (and were preferred until technology improved the quality and durability of the early tubeless tires. Stock wheels are 20" (tubed) and 22.5” (tubeless), the bolt pattern is 10-lugs on 7.25" circle. The center hole is 5.25". Studs are 5/8-18. In 1956, Chevy switched to the 6-lug pattern on the 2-ton trucks. We'll be adding info on the later trucks in the future. |
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Original (Tubed/Bias Ply) size/style tubed tires
If you plan on staying with your original wheels (assuming they are serviceable and correct for your application), let's go tire shopping! The good news is that 20” tube type tires are easily available to fit the original wheels -- even the 1.5 and 2-ton two or three-piece “locking ring” wheels.
For pickups, check the Links Section for specialty retailers offering new tires to fit your original wheels.
For the Big Bolts, most truck tire centers or Ag stores (like Southern States, Agri-Supply, etc.) can find you modern tubed tires to fit. 7.50X20 is a normal size. 8.25X20 can often be used although with a slight decrease in turning radius because the rear edge of the front tire will rub the springs in a hard turn, most people don’t consider this a problem. Just remember to check what kind of wheels you have -- 2-piece locking rim or 3-piece rims are okay. Center split 2-piece wheels are not. Most big truck or Ag tire facilities will have people knowledgeable and willing to work on your multi-piece rims as long as they are not the center splits. Don't even bother trying one of the chain tire retail outlets.
| Upgrading to Modern Wheels and Tires |
When upgrading to modern wheels and tires, you will need to find wheels before you can begin tire shopping, so we'll start with the harder effort first.
Please note: Listing every possible replacement wheel to fit your particular application is well beyond the scope of this article. The point here isn't to present an exhaustive list of what fits and what doesn't, but to educate you as to what to look for, and how to look for it. As long as you know your lug pattern, center hole diameter, etc, and understand the info presented below, you should be well-armed to navigate the myriad possibilities open to you for replacement wheels and tires -- good luck and happy hunting!
1. Wheels
Overview
Before you do anything else, I highly recommend reading the "general information" section in the Accuride catalog, starting with page 36. It includes chart for matching tire size to rim size/widths, pictures of rim shapes (5 degree tube type different rim constructions, and 15 degree tubeless), how to spot damaged rims (very important for old wheels), recommended nut torque, chart with crossover from tube type to tubeless tires (8.25X20 = 9R22.5), correct dual spacing. All very important info that's well worth reading so you know where to go when questions come up un the future.
So, now that you know what you need to fit (on your existing hubs), you say, "Why don't I get some 22.5" wheels and use modern tubeless tires on my AD truck?" Well, easier said than done. To start with, 8X22.5" tires are very hard to find these days. On the plus side, the 9R22.5 tires are made and easy to get at any truck tire store.
I've looked long and hard and have yet to find any newly manufactured 22.5" wheels made with the small 7.25" bolt pattern we use. In 1956 Chevy used that bolt pattern with 22.5" wheels on the 1.5 ton trucks. As far as I know it was only 1.5-tons, as the 2-tons had 6-lug, stud-centered Budd wheels. Best I can tell these wheels were only installed on Chevy trucks from 1956-1959. That makes the wheels somewhat difficult to find. Although I have seen a few trucks with them, and I have found a set for use on my '48 2-ton.
1-tons & 3/4-tons
1.5 & 2-tons
2. Tires
Now that you've found wheels to fit (hopefully!), let's consider your new rubber.
Modern Tubeless tires
The first thing to remember is that the diameter of the tire must match the diameter of the wheel. EXACTLY. i.e., 19.5-inch tires MUST be used on 19.5 inch wheels. With that in mind, new tubeless and radial tires to fit our 1.5 and 2-ton AD trucks are available. The easiest wheels to find seem to be the 19.5" tubeless 10 lug wheels, as found on the Chevy P30 chassis, 3500HD and other trucks in the 80’s until about 2005. Again, 19.5” tires can not be used on 20” wheels; new or used 19.5” wheels must be used. The tallest tire available (without being really wide) in 19.5" is an 8R19.5, and they are about 32" or 33" tall. I think they are intended to be a replacement for 7.50X17, although I am not 100% sure on that. If you replace your stock 7.50X20 tires with the readily available 8R19.5 tires (and new wheels) they will have a smaller outside diameter. Some people don't mind, I personally think they look much too small on a 1.5 or 2 ton truck. With smaller tires you will also lose road speed, not good for our already slow trucks. On the plus side, smaller tires give increased braking performance.
22.5" tires are available with an outside diameter "OD" similar to the original 20" tires used on our trucks, therefore upgrading from 20" to 22.5" wheels and tires (if possible) is to be preferred over the smaller 19.5" wheel/tire swap. For example, 8X22.5 is the tubeless direct replacement (approximate same OD, and approximate same tread width) for 7.50X20. The replacements for 8.25X20 tires are 9R22.5. This info is on page 45 on the Accuride catalog. There are lower profile 22.5" tires that you may use; they will be labeled as 245/75R22.5, or some such mess of numbers. I don't know the details and sizes as to what replaces what for those. To run readily available 9R22.5 tires on your AD 1.5 or 2 ton you need a set of hard to find 22.5 wheels, they are not available new (see wheel section above for details).
A note on Metric tire sizing
Metric tire sizing works like this -- as an example lets use the tire size 245/75R22.5. The first number, 245, is the width of the tire (when mounted on a specified wheel width) measured at the widest point, usually from sidewall to sidewall, this is the "Section Width" (cross section) in millimeters. 75 is the tire's profile or aspect ratio, in this case sidewall height (from rim to tread) is 75% of the tires section width, or about 184mm. Next is "R" for "Radial". And finally 22.5 is the rim diameter in inches measured at the bead seat. The mm measurements can then be converted to inches by dividing the number of millimeters by 25.4 (the number of millimeters in an inch).
| Wheel & Tire Sources |
| Final Thoughts |
Remember When scouting for more modern wheels to fit your truck, the best thing you can have with you is an accurate measurement of your wheel diameter, bolt pattern and center hole diameter. And whether your truck needs a stud-piloted or hub-piloted wheel. New/different/replacement wheels should be test fit before buying, as brake drum interference can be a problem, particularly with 19.5" wheels on some AD big bolts. You will see a LOT of wheels in junkyards and swap meets -- many of them will look like what you need, but WON'T BE! Know what you need! Measure twice and buy once!
Good luck!
Thanks to the following 'Bolters for their help with this article:
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