1926 Hupmobile Tire Fitment Guide

1926 Hupmobile vehicles use four sizes across two model families. The 6 Cyl. uses 30X5.25 and 5.25-20, both for 20-inch wheels, while the Line 8 uses 33X6.00 and 600-21, both for 21-inch wheels. Among currently listed products, 600-21 includes BFGoodrich and Lester offerings, and BFGoodrich lists a 3.00 to 3.75 inch rim width range for that size.

That means year and make are only the starting point. A 1926 Hupmobile owner needs to identify the model first, then confirm whether the car is set up for the antique diameter-by-section size or the numeric size used on the same wheel diameter for that model family. Checking the actual wheel before choosing a tire is especially important on restored cars that may have had wheel or tire changes over the decades.

On a 1926 Hupmobile, 30X5.25 is an antique diameter-by-section size. The first number is the tire's nominal overall diameter in inches, and the second number is the nominal section width in inches. It is a bias-ply size used on the 1926 Hupmobile 6 Cyl., and it corresponds to a 20-inch wheel application within that model's fitment family.

That older style of sizing can look unfamiliar if you are used to modern numeric or metric tire codes. For a restoration, the appeal is that it reflects the language and visual character of the mid-1920s. Before selecting it, compare the existing wheel and any old tire markings on the car so you stay with the same 20-inch fitment path intended for the six-cylinder Hupmobile rather than crossing into the Line 8's larger 21-inch family.

On a 1926 Hupmobile, 600-21 is a numeric bias-ply size. The 6.00 identifies the nominal section width in inches and the 21 identifies the wheel diameter. This size belongs to the 1926 Hupmobile Line 8, not the 6 Cyl., and currently available products include both Blackwall and Wide Whitewall versions from BFGoodrich plus a Blackwall option from Lester.

Numeric sizes like 600-21 are easier for many modern buyers to interpret than the earlier diameter-by-section style, but they still need to be matched to the correct model and wheel. If your Hupmobile is a Line 8 on 21-inch wheels, 600-21 is the active product-supported size to start from. If the car is a 6 Cyl., moving to this size would mean stepping into the wrong wheel diameter family.

For 1926 Hupmobile fitments with currently listed products, sidewall choices appear in the 600-21 Line 8 size. That size is offered in Blackwall from Lester and BFGoodrich, and in Wide Whitewall from BFGoodrich. All of those listed choices are bias-ply, so the sidewall decision is about appearance within a period-style construction rather than choosing between bias-ply and radial behavior.

A blackwall generally suits a more restrained, workmanlike, or early-period presentation, while a wide whitewall creates a more formal visual statement that many owners prefer on upscale late-1920s cars. The right choice depends on how you want the car to read at a glance and what standards your club or judging venue prefers. Matching the sidewall style to the car's trim level and restoration theme usually matters more visually than any other cosmetic tire detail.

Two brands appear in currently listed 1926 Hupmobile applications: Lester and BFGoodrich. Both are offered in the 600-21 size used on the 1926 Hupmobile Line 8. BFGoodrich appears in both Blackwall and Wide Whitewall versions, while Lester is listed in Blackwall for that same 21-inch numeric bias-ply size.

Brand choice on a collector car usually comes down to the exact appearance you want, the sidewall treatment that suits the restoration, and the details of the specific product rather than loyalty to the name alone. Once the model and size are confirmed, compare the visual profile and any published load or rim-width information for that exact tire. That approach is more useful than assuming every tire in the same nominal size will present the same way on the car.

For the 1926 Hupmobile Line 8 in 600-21, Lester is listed as a Blackwall bias-ply tire weighing 20 pounds. BFGoodrich offers a Blackwall version at 31 pounds and a 3.50 Inch Wide Whitewall version at 34 pounds, both with a listed maximum load of 1350 pounds at 36 psi and a stated rim width range of 3.00 to 3.75 inches.

Those differences point to a practical selection process. If appearance is the priority, the whitewall versus blackwall decision will narrow the field immediately. If you are refining a restoration more closely, the listed weight, sidewall style, and published rim-width guidance give you a better basis for choosing than the size code alone. The key is to compare the exact series rather than treating all 600-21 tires as interchangeable in look or published specifications.

Published rim-width guidance appears in the currently listed 600-21 tires for the 1926 Hupmobile Line 8. BFGoodrich specifies a rim width range of 3.00 to 3.75 inches for that size. The 6 Cyl. sizes and the antique-format Line 8 size shown here do not carry additional rim-width figures in the currently listed products.

That makes the wheel itself an important checkpoint before choosing a tire, especially on a car that may have passed through several owners or restorations. Measure the wheel where the bead seats rather than relying on outside-to-outside dimensions. If your Hupmobile is a Line 8 running 600-21, staying inside the published 3.00 to 3.75 inch range is the cleanest path. On other sizes, compare wheel markings and consult a marque specialist if the setup appears different from standard period practice.

The currently listed 1926 Hupmobile products do not show tube-type or tubeless markings in the size field, so the practical assumption for a mid-1920s wire-wheel or demountable-rim application is to verify the exact wheel and tire before setup. All listed fitments here are period-style bias-ply sizes, and on cars of this age, tube use is often tied as much to wheel construction as to the tire itself.

A 1926 Hupmobile owner should inspect the wheel design, rim condition, flap requirements if applicable, and valve-stem arrangement before mounting tires. That step matters more on prewar cars than on later one-piece drop-center wheels because the wheel hardware often determines the tube decision. Matching the tube, flap, and valve-stem configuration to the wheel is part of getting a usable and reliable vintage setup, not just an accessory choice.

A 1926 Hupmobile should be stored in a cool, dry, dark space away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment that can age rubber. Keep the tires properly inflated, and if the car will sit for extended periods, move it occasionally or support it in a way that reduces long-term static loading on one contact patch. Bias-ply tires are especially prone to temporary flat-spotting after long storage.

Good storage habits protect both appearance and drivability. Sidewall cracking, casing stress, and moisture damage often begin long before the tread shows much wear on a collector car that is only driven occasionally. Even if the Hupmobile is displayed more than driven, shielding the tires from light and ozone and avoiding months of uninterrupted weight on the same section of tire will help preserve the shape and finish of a period-style bias-ply setup.

Tires on a 1926 Hupmobile usually age out before they wear out. For collector vehicles, a sensible rule is to evaluate tires closely once they are about five to seven years old and to treat around ten years as the point where replacement deserves serious consideration regardless of tread depth. The DOT date code on the tire is the best way to establish age when a code is present.

That schedule matters because a vintage car may see very low mileage yet still develop sidewall hardening, internal degradation, or cracking from time and environment. Waiting for visible tread wear is rarely the right standard on a Hupmobile that spends much of its life parked, trailered, or driven only to events. If the car is new to you, checking age is one of the first maintenance steps worth taking before any extended road use.

Tires on a 1926 Hupmobile should be checked before every drive and again before any longer outing. Look for sidewall cracking, cuts, bulges, uneven tread wear, and pressure loss, and inspect the spare as carefully as the four tires on the car. On a vehicle of this age, valve stems and any tube-related hardware deserve the same attention because they can fail even when the casing still looks presentable.

Frequent inspections matter more on a low-use prewar car than on a regularly driven modern vehicle because problems can develop while the car is sitting. A Hupmobile that has been stored since the last event may look fine at a glance and still need air, a closer crack check, or a spare-tire review before heading out. Making tire inspection part of your pre-drive ritual is one of the simplest ways to avoid an interruption on the road.

A 1926 Hupmobile 6 Cyl. would have been fitted in the bias-ply era, and the relevant sizes for that model family are 30X5.25 and 5.25-20 on 20-inch wheels. Those two sizes reflect period conventions used in the 1920s, when antique diameter-by-section markings and later numeric designations could both appear within the market. The original construction type would have been bias-ply, not radial.

For restoration work, the main question is which of those 20-inch period sizes matches the exact wheel and configuration on your car. Market differences, production changes, and decades of service repairs can all affect what is on the car today. If you are chasing factory-authentic fitment for judging, compare any surviving literature and consult Hupmobile club resources or marque specialists rather than relying only on what a previous owner mounted.

Correct tire fitment matters on a 1926 Hupmobile because judges and knowledgeable enthusiasts often notice tire construction, size format, wheel diameter, and sidewall style immediately. A six-cylinder car shown on Line 8-sized tires, or a car wearing a sidewall treatment that clashes with its restoration theme, can look wrong even before anyone studies the finer details. On a prewar car, tire choice is a visible part of the vehicle's authenticity.

Showing standards vary by club and event, so the ideal tire is not always the same for every owner. Some venues reward strict period correctness in size and appearance, while others are more accommodating if the overall look remains faithful to the era. Before finalizing a set, decide whether the Hupmobile is being prepared for touring, local display, or formal judging, then align the tire size and sidewall style with those expectations.

On a 1926 Hupmobile, antique-format sizes such as 30X5.25 and 33X6.00 express nominal overall diameter first and section width second. Numeric sizes such as 5.25-20 and 600-21 use nominal section width first and wheel diameter second. Both are bias-ply period conventions, but they belong to different tire-marking systems that were used during the 1920s as the industry evolved.

For authenticity, that distinction matters because the visual language on the sidewall should suit the exact restoration goal as well as the car's wheel diameter. An owner trying to preserve an especially early 1920s look may prefer the antique-style marking, while another may follow the numeric size already associated with the car's wheel setup. The important point is to stay within the correct model family and wheel diameter rather than mixing six-cylinder and Line 8 tire groups.

1926 Hupmobile tires can be used on the road when they are the correct size, in sound condition, properly mounted, and operated within the limitations of both the tire and the car. The currently listed 600-21 products do not show speed-rating letters, and all listed fitments for 1926 Hupmobile are bias-ply designs, which means the car should be driven with the manners and pace appropriate to a prewar chassis rather than as if it were a modern sedan.

In real-world use, the Hupmobile's own brakes, steering feel, suspension design, and overall age are usually the bigger constraint than the idea of a posted highway speed alone. A careful owner treats the whole car as a 1920s machine: moderate speeds, generous following distance, smooth inputs, and frequent checks. If the car has sat for a long period, tire condition should be confirmed before any extended route that includes sustained road speed.

Inflation pressure on a 1926 Hupmobile should follow the vehicle's original specifications where available and the tire maker's limits for the exact tire being used. Among currently listed products, BFGoodrich 600-21 tires show a maximum load of 1350 pounds at 36 psi. That figure is a tire rating point, not a universal instruction to inflate every 1926 Hupmobile tire or every Hupmobile size to the same pressure.

The right approach is to match pressure to the specific size, product, wheel, and use case instead of borrowing a number from a different tire family. A six-cylinder Hupmobile on 20-inch tires should not automatically use a pressure associated with the Line 8's 600-21 fitment. If you have the owner's literature, use it as the starting point, then confirm that the selected reproduction tire's published limits and recommendations are compatible with that setup.

Before taking a 1926 Hupmobile on a longer drive, inspect each tire for cracking, cuts, bulges, exposed cords, irregular wear, and correct inflation, and do not forget the spare. Check the valve stems, wheel hardware, and overall bead seating, especially on a car that has been parked for long periods. Because these are period-style bias-ply fitments, a slow walk-around and hands-on inspection can reveal issues that are easy to miss at a glance.

Tires are only one part of the preparation, but they are one of the few areas that directly affect every mile of the trip. On a Hupmobile of this age, combine the tire check with a broader review of brakes, steering, wheel bearings, fluids, and cooling system condition before leaving home. That routine helps turn a long drive into a manageable vintage-car outing rather than an unplanned roadside repair session.