The 1928 Pontiac 6 Cyl. comes from an important early period for Pontiac, when the brand was establishing itself as a value-minded companion to Oakland with practical six-cylinder motoring and distinctly late-1920s styling. Buyers looking after one of these cars are usually balancing roadworthiness with the visual character that makes a pre-war automobile feel right. Tire fitment centers on two bias-ply sizes, 29X4.75 and 4.75-20, and those two designations need to be interpreted carefully because they come from different sizing conventions. The real decision is confirming which wheel setup is on the car and then choosing a tire that suits restoration priorities, stance, and intended use.
Which Tire Size Is Right for The 1928 Pontiac 6 Cyl.
The 1928 Pontiac 6 Cyl. uses two primary tire sizes, and the first step is confirming which wheel setup is actually on the car. Both are bias-ply fitments, but they differ by sizing convention and rim diameter, so selecting the right tire starts with identifying the exact wheels rather than choosing by appearance alone.
The 29X4.75 size uses an older diameter-by-section format in which 29 refers to the tire's approximate overall diameter and 4.75 refers to its nominal section width. It is a bias-ply fitment suited to the kind of wheel and tire presentation expected on a late-1920s automobile. This format is less familiar to modern buyers, so it is especially important to confirm the wheel dimensions already on the car. It is a useful choice when preserving an early-car look matters as much as basic fitment.
The 4.75-20 size is a numeric bias-ply designation, with 4.75 indicating the nominal section width and 20 indicating the rim diameter in inches. That makes it easier for many buyers to interpret because the wheel diameter is built directly into the size code. On a 1928 Pontiac 6 Cyl., this size belongs on a 20-inch wheel and should be matched to the car's actual rim before moving forward. It is the size to evaluate when the car retains or uses a 20-inch vintage wheel setup.
The covered sub-model fitment is straightforward in name but still requires attention because the Pontiac 6 Cyl. Base can use more than one tire size. Checking the actual wheel and tire setup on the car matters more here than trim identification alone.
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1928 Pontiac 6 Cyl. Base
The 1928 Pontiac 6 Cyl. Base is associated with both 29X4.75 and 4.75-20 bias-ply tires. That means tire selection begins with confirming which wheel diameter is on the vehicle, then choosing the period-style bias-ply fitment that matches the car's current restoration or driving setup.
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Frequently Asked Questions
Common questions for the 1928 Pontiac 6 Cyl. usually center on interpreting the two vintage tire sizes, confirming wheel fitment, and choosing a bias-ply tire that suits both restoration appearance and safe road use.
Tire Size & Fitment
What tire size fits a 1928 Pontiac 6 Cyl.?
The 1928 Pontiac 6 Cyl. uses two primary tire sizes: 29X4.75 and 4.75-20. Both are bias-ply fitments, but they are not just two ways of writing the same size. They belong to different sizing conventions, and the car's actual wheel setup determines which one applies.
The practical step is to inspect the wheels already on the vehicle before choosing a tire. A 4.75-20 tire is meant for a 20-inch rim, while 29X4.75 uses an antique diameter-by-section format that should be matched carefully to the wheel and overall setup on the car. On a restored or modified pre-war vehicle, tire choice should follow wheel confirmation rather than assumptions.
What size rim does a 1928 Pontiac 6 Cyl. use?
Rim size depends on which primary tire size is on the car. The 4.75-20 fitment uses a 20-inch rim, while the 29X4.75 fitment is associated with a different wheel setup. Since both sizes appear on the 1928 Pontiac 6 Cyl., wheel confirmation is the first fitment check.
Looking only at the tire sidewall is not enough if the car has been apart for restoration or has had wheels changed over the years. Measure the wheel diameter directly and confirm that it matches the tire size being considered. That step helps prevent ordering a vintage-style bias-ply tire that looks appropriate but does not match the wheels actually installed on the vehicle.
What does 29X4.75 mean on a 1928 Pontiac 6 Cyl.?
On the 1928 Pontiac 6 Cyl., 29X4.75 is an antique diameter-by-section size. The 29 refers to the tire's approximate overall diameter, and 4.75 refers to its nominal section width. Unlike a modern metric radial or a numeric size such as 4.75-20, the first number is not the rim diameter.
That difference matters because modern buyers often read the first number as a wheel size when it is actually an outside tire dimension. The safest approach is to verify the wheel and compare the existing tire setup on the car before choosing a replacement. On an early Pontiac, getting the vintage sizing convention right is just as important as matching the general width or appearance.
Choosing the Right Tire
What should I consider when choosing a 29X4.75 or 4.75-20 tire for a 1928 Pontiac 6 Cyl.?
Start with the correct primary size for the wheels on the car, because the 1928 Pontiac 6 Cyl. uses both 29X4.75 and 4.75-20 depending on setup. Both are bias-ply fitments, so the main selection issue is not radial versus bias-ply, but confirming the proper vintage sizing system and wheel diameter.
After that, think about how the car will be used and how closely the owner wants to preserve a traditional pre-war presentation. A touring car that sees occasional road miles still needs the correct wheel match, sound clearances, and a tire that suits the vehicle's visual character. On an older restoration, it is wise to inspect wheels, tubes, and rim condition before mounting new tires.
How do I choose between the available 1928 Pontiac 6 Cyl. tire sizes?
The choice between 29X4.75 and 4.75-20 is determined by the wheel setup rather than personal preference. A 4.75-20 belongs on a 20-inch rim, while 29X4.75 follows an older sizing method that identifies approximate tire diameter and section width. Both remain bias-ply options for this Pontiac.
A car from 1928 may have been restored more than once, and wheels are not always the same as what an owner expects to find. Measure the rims, read the markings on any existing tires, and compare the overall setup before deciding. That extra check helps keep the tire choice aligned with the car's hardware, stance, and intended road use.
Why does choosing the correct vintage tire format matter on a 1928 Pontiac 6 Cyl.?
Vintage tire formats matter because 29X4.75 and 4.75-20 communicate size in different ways, even though both are legitimate fitments for the 1928 Pontiac 6 Cyl. One format uses approximate outside diameter and section width, while the other uses nominal width and a stated rim diameter. Mixing those systems up can lead to a mismatch.
On a pre-war car, the wheel, tire, and body proportions are closely tied to the way the car sits and drives. Choosing by appearance alone can create problems with wheel fit, clearance, or overall presentation. Reading the size correctly and matching it to the actual wheels on the car is the best way to keep a replacement tire consistent with the vehicle's setup.
Restoration & Appearance
Which tire should I choose for a period-style 1928 Pontiac 6 Cyl.?
A period-style 1928 Pontiac 6 Cyl. should stay with the correct primary bias-ply size for the wheel setup on the car, either 29X4.75 or 4.75-20. Both sizes suit the vehicle's late-1920s character far better than a modern-looking substitute in the wrong format or profile.
The key is matching the tire to the actual wheels and to the restoration goal. Some owners want a car that looks appropriate for show presentation, while others prioritize touring use with a traditional appearance. When exact originality matters, compare the tire choice against marque-specific references and the car's own restoration history before making the final decision.
Does correct tire fitment matter for a 1928 Pontiac 6 Cyl. restoration?
Correct tire fitment matters a great deal on a 1928 Pontiac 6 Cyl. because the tire size influences more than basic usability. It affects the car's visual proportions, ride height impression, and the overall authenticity of a pre-war restoration. Using the proper bias-ply size helps preserve the vehicle's intended character.
Restoration-minded buyers should treat tire selection as part of the car's finished presentation, not as an afterthought. A size that matches the wheel correctly will usually look more natural under the fenders and complement the car's era. Even on a driver-quality restoration, checking size format, wheel diameter, and overall appearance is worth the effort before committing to new tires.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1928 Pontiac 6 Cyl.?
Yes. Modifications can affect tire fitment on a 1928 Pontiac 6 Cyl., especially if the car has replacement wheels, altered suspension height, brake updates, or bodywork changes from an older restoration. Since this Pontiac can use more than one primary tire size, changes to the vehicle can make assumptions about fitment less reliable.
A careful check should include wheel diameter, wheel width, tire clearance at the fenders, and steering clearance through the full range of motion. Even small differences in an early-car setup can matter. On a modified Pontiac, measuring the current wheels and inspecting available space around the tire is more useful than relying on the car's model name alone.
What should I inspect before driving a 1928 Pontiac 6 Cyl. on new tires?
Before driving a 1928 Pontiac 6 Cyl. on new tires, inspect the wheels, mounting surfaces, valve hardware, and overall tire condition after installation. The tires should seat properly, hold pressure consistently, and clear the body and suspension through steering movement. On an older car, the condition of the rims deserves as much attention as the tires themselves.
A short local shakedown drive is a smart next step before any longer outing. Recheck inflation, look for rubbing marks, and watch for signs of air loss or uneven stance after the first miles. Since collector cars often sit for long periods, it also helps to confirm that wheel fasteners are secure and that no age-related cracking or damage is present elsewhere in the setup.
How should tires on a collector 1928 Pontiac 6 Cyl. be maintained?
Tires on a collector 1928 Pontiac 6 Cyl. should be maintained with regular pressure checks, routine visual inspection, and careful storage habits. Even a bias-ply tire with good tread can age out from time, sunlight, heat, or long periods of inactivity. Sidewall cracking, bulges, cuts, and persistent air loss all deserve prompt attention.
Collector cars often accumulate fewer miles, so condition matters more than tread depth alone. Keeping the car in a cool, dry space and moving it occasionally can help reduce flat spotting and prolonged stress in one position. Before any tour or event, inspect the full tire and wheel assembly again so the car is road-ready as well as visually presentable.
