1959 Humber Hawk Tires

The 1959 Humber Hawk uses two tire sizes: 640-15 in bias-ply construction and 175R15 in radial construction. Both are 15-inch fitments, so the main difference is not wheel diameter but the sizing system and tire construction used on the car.

That means the first choice is whether the Hawk will stay with a traditional bias-ply setup or use a radial tire format. Bias-ply usually appeals to restoration-minded owners, while the radial route changes the construction style and should be checked against the actual wheel width and the car's current suspension and clearance setup.

The 1959 Humber Hawk uses a 15-inch rim diameter with both of its primary tire sizes. That applies to the 640-15 bias-ply fitment and the 175R15 radial fitment, so wheel diameter stays consistent even though the tire construction can change.

Rim diameter is only one part of the fitment picture. Wheel width still matters, especially when comparing the original-style 640-15 to radial alternatives, so it is smart to confirm the actual wheel on the car before selecting tires. Cars that have been restored or modified may no longer be using the original wheel setup.

The 1959 Humber Hawk Base can use the same two tire directions as the core model: 640-15 bias-ply or 175R15 radial. There is no separate sub-model-only tire size here, so the fitment choice comes down to construction and how the car is intended to look and drive.

That consistency makes the Base model easier to shop for, but it does not eliminate the need to verify the wheel and vehicle setup. A Hawk running original-style wheels may point an owner toward the classic 640-15, while a car already converted for radial use should still have wheel width and overall clearance checked carefully.

On a 1959 Humber Hawk, 640-15 is a bias-ply tire size. It is the traditional numeric fitment for the car and is offered in classic bias-ply form, including blackwall, narrow whitewall, and wide whitewall versions depending on the tire series and brand selected.

That matters because a bias-ply tire affects both the car's appearance and the way the overall setup is approached. Owners keeping a restoration-oriented presentation often stay with 640-15, while anyone considering a radial alternative should treat that as a construction change and confirm wheel width, clearance, and the car's current mechanical condition before making the switch.

Radial equivalents for 640-15 include 175R15 as the 80-series metric radial, P175/75R15 as the P-metric 75-series radial, and P185/70R15 as the P-metric 70-series radial. These are equivalent-size references for the Humber's original-style 640-15 bias-ply fitment, not alternate primary fitments that should be assumed interchangeable.

Each equivalent represents a different sizing convention and profile family, so the choice should be made carefully. A recommended rim-width range of 5 to 6 inches is tied to those radial equivalents, and the final decision should also account for the actual wheel on the car, plus steering, fender, and suspension clearance before the conversion is finalized.

A conversion from 640-15 bias-ply to a radial setup on a 1959 Humber Hawk starts with confirming the wheel diameter and wheel width already on the car. The commonly referenced radial equivalents are 175R15, P175/75R15, and P185/70R15, with a 5 to 6 inch rim-width range noted for those equivalent radial options.

The next step is to compare the full vehicle setup rather than focusing on size code alone. Steering clearance, fender space, suspension condition, and the intended use of the car should all be reviewed. A Hawk that has aftermarket wheels, changed ride height, or long-neglected front-end components deserves extra attention before any construction change is put into service.

Choosing a 640-15 tire for a 1959 Humber Hawk starts with confirming that the car is staying with its bias-ply fitment rather than moving to the 175R15 radial path. From there, the important comparisons are sidewall style, brand, tire series, rim-width suitability, and useful specification details such as load figures where they are stated.

The right selection depends on how the Hawk is being used and presented. A blackwall tire gives a restrained traditional look, while narrow or wide whitewalls change the car's visual character noticeably. It also helps to confirm that the wheel matches the tire's intended rim-width range so appearance and fitment are working together rather than at odds.

For the 1959 Humber Hawk's 640-15 bias-ply fitment, available sidewall styles include blackwall, narrow whitewall, and wide whitewall. Those sidewall treatments appear across several classic tire offerings, so the owner has meaningful appearance choices without changing away from the car's traditional tire size.

Sidewall style has a strong effect on how a late-1950s British saloon presents itself. Blackwall tends to look understated and practical, while whitewall options give the car a more formal period-style presence. The best choice usually depends on the restoration theme, wheel and trim combination, and whether the goal is a subtle road car or a more dressed-up show-oriented appearance.

The 1959 Humber Hawk's 640-15 bias-ply size is available from BFGoodrich, Firestone, Avon, and Excelsior. Those brands cover multiple classic tire series, including blackwall and whitewall options, so the buyer is comparing more than a single visual style within the original-style size.

Brand choice should be weighed alongside the specific tire series, sidewall treatment, and wheel compatibility rather than as a stand-alone decision. One owner may focus on a broad whitewall presentation, while another may prefer a blackwall tire with a more restrained touring look. Matching the tire's stated specifications to the car's actual wheel setup remains just as important as brand preference.

A period-style 1959 Humber Hawk usually starts with the 640-15 bias-ply size, since that keeps the car in its traditional construction and sizing format. Within that size, the real choice becomes how formal or restrained the car should look through blackwall, narrow whitewall, or wide whitewall presentation.

That does not make every 640-15 automatically correct for every restoration goal, especially when originality standards are high. Owners pursuing a very exact finish should compare tire appearance against marque references, period photos, and restoration documentation. For many cars, though, staying with the bias-ply size is the clearest starting point for a traditional Humber look.

Tire construction changes the visual character of a restored 1959 Humber Hawk more than many buyers expect. A 640-15 bias-ply keeps the car in a classic late-1950s presentation, while a 175R15 radial moves the Hawk into a more modern tire format even when the wheel diameter remains the same.

That difference matters most when the restoration aims to preserve the car's original-era atmosphere. Bias-ply tires tend to complement period styling and whitewall treatments more naturally, while radial sizing may appeal more to owners prioritizing regular road use. The best match depends on whether the restoration is centered on visual authenticity, touring use, or a balanced compromise.

Yes, modifications can affect tire fitment on a 1959 Humber Hawk even when the size being considered is one of the standard 15-inch options. Changes such as aftermarket wheels, altered wheel width, suspension work, ride-height changes, or body repairs can all influence how a 640-15 or 175R15 setup sits and clears.

A car that looks stock from the outside may still have non-original wheel specifications, so it helps to verify the hardware before ordering tires. Measuring wheel width and checking steering and fender clearance are sensible steps, especially if the Hawk has already been changed from bias-ply to radial construction or has been rebuilt over several decades.

Before driving a 1959 Humber Hawk on new tires, inspect the wheels for correct diameter and sound condition, then check that the tires are seated properly and inflated appropriately for the setup being used. It is also wise to look over the suspension, steering components, and brake system, since tire replacement often reveals problems that were masked by old rubber.

A short, careful test drive is a smart follow-up rather than heading straight onto a long trip. During that first outing, pay attention to pull, vibration, unusual rubbing, or inconsistent steering feel. Rechecking inflation and doing another visual inspection after a few miles can help catch clearance or mounting issues before they turn into roadside problems.

640-15 tires on a collector 1959 Humber Hawk should be maintained with regular pressure checks, visual inspections, and attention to age-related condition even if the car sees limited mileage. Bias-ply collector tires deserve close watching for sidewall cracking, tread separation signs, cuts, bulges, and slow air loss that may develop during long storage periods.

Storage conditions matter almost as much as miles driven. Keeping the Hawk away from prolonged sunlight, heat, moisture, and ozone sources helps preserve the tires, and occasional movement can reduce flat-spotting from extended parking. Any tire that shows visible deterioration or questionable behavior on the road deserves professional inspection before the car is driven further.