1958 Humber Hawk Tires

The 1958 Humber Hawk uses two applicable tire sizes: 640-15 in a bias-ply construction and 175R15 in a radial construction. Both are 15-inch tire fitments, so the choice is not about changing wheel diameter first, but about selecting the construction and sizing format that suits the car and its intended use.

That distinction matters because a numeric bias-ply size and a Euro-metric radial size do not present the same buying decision. Owners restoring the car's period look often start with 640-15, while owners considering radial behavior typically focus on 175R15. Before choosing, confirm the actual wheel size on the car and whether it still carries its original-style wheel setup.

The 1958 Humber Hawk uses a 15-inch rim with both of its applicable tire sizes. That applies whether the car is fitted with the 640-15 bias-ply size or the 175R15 radial size, so rim diameter remains consistent even though the tire construction and size format change.

Rim diameter is only part of the fitment picture. Wheel width should also be checked, especially when comparing bias-ply and radial options or evaluating a radial equivalent for the 640-15 size. A car that has had replacement wheels installed over the years may still have 15-inch rims but not the same width or profile that the original-style fitment expects.

The 1958 Humber Hawk Base follows the same fitment pattern as the model overall, using either 640-15 bias-ply tires or 175R15 radial tires. There is no separate Base-only wheel diameter to sort out here, which keeps the fitment question fairly simple compared with vehicles that change size by trim or package.

The practical decision is choosing which of those two directions matches the car. A restoration-oriented Base model may lean toward the traditional 640-15 look, while a road-driven car may be evaluated around the 175R15 radial format. Even with shared fitment, the actual wheels on the car should be checked before purchase if the vehicle has seen decades of service or modification.

On the 1958 Humber Hawk, 640-15 is the bias-ply tire size. It is the vintage numeric fitment used on a 15-inch rim and is the format associated with the car's traditional tire presentation. The radial-format size associated with this Hawk is 175R15 rather than a radial version of the 640-15 designation itself.

That matters because a buyer looking at 640-15 products is choosing among bias-ply constructions, sidewall treatments, and vintage tire series rather than comparing radial builds in the same size code. Owners changing away from that format should confirm wheel width, vehicle stance, and clearance, since moving from a bias-ply size to a radial alternative is a fitment decision, not just a naming difference.

Radial equivalents for 640-15 include 175R15 as an 80-series metric radial, P175/75R15 as a P-metric 75-series radial, and P185/70R15 as a P-metric 70-series radial. These are the recognized radial alternatives tied to the Humber Hawk's original bias-ply size, and they all stay within the same general 15-inch fitment family.

Each equivalent uses a different sizing convention, so the choice is not purely cosmetic. The recommended rim-width range for the equivalent path is 5 to 6 inches, and clearance should still be checked at the fenders and steering components. A radial equivalent can be a useful alternative, but it should be evaluated against the actual wheel and vehicle setup rather than assumed to interchange automatically.

Start by confirming the wheel diameter and width actually on the car, then compare the intended radial size against the existing 640-15 setup. For a 1958 Humber Hawk, the recognized radial path includes 175R15, P175/75R15, and P185/70R15, with a recommended rim-width range of 5 to 6 inches for the equivalent route.

Beyond the wheel itself, inspect steering clearance, fender clearance, suspension condition, and the car's overall stance before making the change. An older sedan may have replacement wheels, sagging springs, or previous body work that affects fitment. Owners should also decide whether the goal is traditional appearance, radial road manners, or a balanced compromise between the two.

The first consideration is whether 640-15 matches the way the car is meant to be used, since it is the Humber Hawk's traditional bias-ply size. After that, compare sidewall style, tire series, brand, rim-width compatibility, and load specifications where they are stated. Those details shape both the look of the car and how closely the tire suits a period-style setup.

A blackwall bias-ply gives a more restrained presentation, while whitewall options create a stronger late-1950s visual statement. Rim-width recommendations also deserve attention because not every 640-15 product is intended for exactly the same wheel range. Choosing carefully within the size matters more than simply picking any tire with the correct numeric code on the sidewall.

For the 1958 Humber Hawk's 640-15 bias-ply fitment, available sidewall styles include blackwall, narrow whitewall, and wide whitewall. That gives owners a useful range of visual choices, from a plain traditional black sidewall to a more dressy whitewall presentation that suits many British and American cars of the late 1950s.

Sidewall style changes the car's appearance more than many buyers expect, especially on a sedan with upright body lines and visible wheel openings. The right choice depends on the look being pursued rather than a claim of exact originality. Owners interested in a restoration-oriented presentation should compare tire photos with period references for cars trimmed similarly to their own.

The 1958 Humber Hawk's 640-15 bias-ply size is available from BFGoodrich, Firestone, Avon, and Excelsior. Those brands appear across several vintage tire series and sidewall treatments, so the buying choice is broader than a single brand or a single visual style within the Humber's traditional fitment.

Brand becomes most useful as a way to sort product character, sidewall presentation, and specification details rather than as a ranking exercise. Some options focus on blackwall simplicity, while others offer narrow or wide whitewalls for a stronger period-style appearance. Comparing rim-width guidance and load figures where shown will usually be more helpful than choosing strictly by brand name alone.

A period-style 1958 Humber Hawk usually starts with the 640-15 bias-ply size because it preserves the vintage numeric format and the traditional tire profile associated with the car's era. Within that size, blackwall and whitewall options are both available, along with several classic bias-ply series from established vintage-tire brands.

The right appearance choice depends on how the car is being presented. A restrained touring-sedan look may favor blackwall, while a more formal or dressy restoration may lean toward narrow or wide whitewall styling. When exact originality matters, compare the tire's visual treatment against marque references, period photography, or restoration records specific to the individual car.

Tire construction affects both the look and stance of a restored 1958 Humber Hawk because bias-ply and radial tires present the sidewall and tread profile differently. The 640-15 bias-ply format gives the car a more traditional late-1950s visual character, while the 175R15 radial format introduces a more modern sizing convention and overall presentation.

That visual difference matters on a car with formal body lines and prominent wheel openings. Owners restoring for authenticity of appearance often begin with the bias-ply size, then choose the sidewall treatment that best matches the car's trim level and intended look. A radial may still be appropriate, but it should be selected with the understanding that construction changes the visual impression.

Yes, modifications can affect tire fitment on a 1958 Humber Hawk even when the tire size itself is correct. Replacement wheels, altered wheel width, suspension changes, body repairs, or lowered ride height can all change how a 640-15 or 175R15 tire sits in the wheel opening and how much clearance remains during turning or suspension travel.

That is why the actual car should be measured before settling on a tire path, especially if its history is uncertain. A Hawk that now carries aftermarket wheels may still use a 15-inch rim but not the same width or contour expected by the original-style setup. Checking steering sweep, fender clearance, and wheel-to-suspension space is time well spent.

Before driving a 1958 Humber Hawk on new tires, inspect the wheels for condition and correct size, confirm valve stems and mounting hardware are in good order, and verify inflation pressure matches the tire being used. It also helps to check the suspension, steering components, and alignment so the new tires are not being asked to compensate for worn chassis parts.

The first miles on a collector car are also a good time to watch for rubbing, pulling, vibration, or uneven clearance at full steering lock. A fresh tire does not erase old mechanical issues, and a car that has sat for long periods may reveal them quickly. Rechecking pressure and a visual inspection after initial road use is a sensible habit.

640-15 tires on a collector 1958 Humber Hawk should be maintained with regular pressure checks, visual inspections for cracking or cuts, and periodic review of tread and sidewall condition even if the car is driven sparingly. Collector vehicles often accumulate age before mileage, so time and storage conditions matter just as much as road wear.

Storage plays a major role in preserving bias-ply tires. Keeping the car away from prolonged sunlight, moisture, excess heat, and ozone sources helps protect the rubber, and moving the vehicle occasionally can reduce long-term flat spotting. Before any longer drive, inspect for air loss, bulges, or damage and make sure the tires still match the wheel setup on the car.