1968 Triumph TR3, TR4 & TR4A Tires

The 1968 Triumph TR3, TR4 & TR4A uses two primary tire sizes: 590-15 in bias-ply construction and 165R15 in radial construction. Both fitments use a 15-inch rim, so the main distinction is not wheel diameter but tire construction and sizing format.

Choosing between them starts with the wheel already on the car and the type of driving or presentation that matters most. A 590-15 keeps the traditional numeric bias-ply format, while 165R15 opens up a wider range of radial choices and sidewall styles. If the car has replacement wheels, confirm actual wheel width before selecting a tire.

Both primary tire sizes for the 1968 Triumph TR3, TR4 & TR4A use a 15-inch rim. That applies to the 590-15 bias-ply fitment and the 165R15 radial fitment, so rim diameter stays consistent even though the tire constructions differ.

Rim diameter is only part of the fitment picture, especially on older sports cars that may have seen wheel changes over time. Width matters too. Many 165R15 radial options are intended for wider rim ranges than the 590-15 bias-ply choices, so it is smart to measure the wheel before moving from one construction type to the other.

590-15 is a vintage numeric bias-ply tire size. The 590 refers to an approximate 5.90-inch nominal section width, and the 15 identifies the rim diameter in inches. On the 1968 Triumph TR3, TR4 & TR4A, it is the traditional bias-ply fitment option.

That older sizing format does not read the same way as a modern metric radial size, which is why it often causes confusion. In practical terms, it points the buyer toward a bias-ply tire with a classic appearance and narrower wheel requirements. Before changing away from it, compare the car's wheel width and the intended visual style.

590-15 is a bias-ply tire size for the 1968 Triumph TR3, TR4 & TR4A. It uses the older numeric sizing system and represents the traditional construction option offered alongside the 165R15 radial fitment on the same 15-inch rim diameter.

That matters because bias-ply and radial tires differ in both appearance and how they suit a given wheel width. A 590-15 keeps the car in a more period-style tire format, while a radial choice may require a different wheel-width match. On a car with replacement wheels or altered suspension, confirm the complete setup before switching constructions.

Radial equivalents for 590-15 include 165R15 as an 80-series metric radial, P165/75R15 as a P-metric 75-series radial, and P175/70R15 as a P-metric 70-series radial. A recommended rim-width range of 4 to 5 inches is associated with these equivalents.

Those sizes are useful alternatives, but they are not automatic substitutes simply because they share a similar role. The car's actual wheel width, overall clearance, and current ride height still need to be checked. On a lightly modified Triumph, even a reasonable equivalent should be compared carefully before replacing the original bias-ply size.

Either can be appropriate because the 1968 Triumph TR3, TR4 & TR4A has both a 590-15 bias-ply fitment and a 165R15 radial fitment. The decision usually comes down to whether the priority is a more traditional period-style presentation or a radial tire format with broader product variety.

A bias-ply choice keeps the car visually closer to an earlier tire style, while 165R15 radials are offered in more brands, series, and sidewall treatments. The wheel on the car should guide the final choice, since rim-width compatibility can differ between the two fitments. Matching all four tires in one construction type is also the safer approach.

Start with the correct size and construction for the wheel setup on the car. The 1968 Triumph TR3, TR4 & TR4A uses either a 590-15 bias-ply tire or a 165R15 radial, both on 15-inch rims, so wheel width and intended construction are the first filters.

After that, compare the tire's visual character and specifications that affect compatibility. Sidewall style, tire series, brand, rim-width range, and load figures all help separate one option from another. A car aimed at period-style appearance may lean toward 590-15, while a road-driven setup may point toward the wider 165R15 radial selection.

The available sidewall styles for the 1968 Triumph TR3, TR4 & TR4A include blackwall, narrow whitewall, and wide whitewall. Those styles appear across both fitment paths, with blackwall offered in both 590-15 and 165R15, and whitewall options available in several radial and bias-ply products.

Sidewall choice affects the look of the car more than the fitment itself, but it can strongly influence how finished the vehicle feels. A blackwall generally gives a simpler sporting presentation, while narrow or wide whitewalls create a more restoration-oriented look. Once the correct size is established, sidewall style becomes one of the most visible decisions.

Tires for the 1968 Triumph TR3, TR4 & TR4A are available from BFGoodrich, Avon, Michelin, Vredestein, Firestone, Coker Classic, and American Classic. The broadest brand spread appears in 165R15 radial form, while 590-15 bias-ply choices are available from BFGoodrich and Avon.

Brand matters mostly as part of the larger selection picture rather than as a ranking tool. Some brands focus on traditional blackwall bias-ply presentation, while others offer whitewall radials or specialty series within 165R15. Once size and construction are settled, the better comparison points are sidewall style, series character, rim-width range, and appearance goals.

For a period-style 1968 Triumph TR3, TR4 & TR4A, the 590-15 bias-ply size is the natural starting point because it preserves the vintage numeric format and traditional tire presentation. Blackwall and wide whitewall bias-ply options are both available within that size.

The right visual result depends on how the car is being finished. Some owners want the leaner sporting look of a blackwall, while others prefer a more restoration-oriented whitewall treatment. If exact originality matters, compare the chosen tire style against marque references or period vehicle documentation rather than assuming any available sidewall is historically exact.

Tire construction changes the overall visual impression of a restored 1968 Triumph TR3, TR4 & TR4A. A 590-15 bias-ply keeps the car in an older sizing language and tends to support a more traditional presentation, while a 165R15 radial gives the car a later, more modern tire format.

That difference matters even before the car moves, especially on a compact British sports car where tire shape is easy to notice. Sidewall treatment adds another layer, since blackwall, narrow whitewall, and wide whitewall options each create a different personality. Restoration-minded buyers usually choose construction first, then refine the final look through sidewall style.

Yes, modifications can affect tire fitment on a 1968 Triumph TR3, TR4 & TR4A even when the tire size itself is correct. Aftermarket wheels, changes in wheel width, suspension alterations, or body and fender work can all influence how a 590-15 or 165R15 tire sits and clears.

That is especially important when moving between bias-ply and radial tires, because the construction choice may also change the wheel-width requirements. A Triumph that has been lowered or fitted with non-original wheels should have steering clearance, fender clearance, and wheel dimensions checked carefully. Tire size alone does not confirm that the complete setup is still compatible.

Before driving a 1968 Triumph TR3, TR4 & TR4A on new tires, inspect the wheels, valve stems, and the tire's installed clearance at full steering lock. It also makes sense to confirm inflation pressure, check for any rubbing points, and make sure all four tires match the intended size and construction choice.

On a collector car, the rest of the chassis deserves attention too. Worn suspension bushings, loose steering parts, or tired shocks can affect how the new tires behave on the road. A short local drive followed by a second inspection is a smart habit, especially after changing from an older bias-ply setup to radial tires.

Collector-car tires on a 1968 Triumph TR3, TR4 & TR4A should be maintained with regular pressure checks, visual inspections, and careful storage habits. Whether the car is running 590-15 bias-ply tires or 165R15 radials, look for cracking, bulges, cuts, uneven wear, and slow air loss before and after periods of storage.

Low annual mileage does not remove the need for inspection. Cars that sit for long stretches benefit from being stored away from prolonged sunlight, excess heat, moisture, and ozone sources, and the tires should be checked before any longer drive. A simple walk-around can catch aging or clearance issues before they become a road-use problem.