1971 Triumph GT6 Tires

The 1971 Triumph GT6 uses two primary tire sizes: 155R13 in radial construction and 560-13 in bias-ply construction. Both are 13-inch fitments, but they represent different sizing systems and different approaches to replacing tires on a small British sports coupe.

The practical choice is deciding which construction belongs on the car as it sits today. A GT6 kept close to period presentation may stay with 560-13 bias-ply tires, while a radial-equipped setup centers on 155R13. Wheel width, overall tire proportions, and the car’s current suspension and clearance should all be confirmed before changing from one construction style to the other.

Both primary tire sizes for the 1971 Triumph GT6 use a 13-inch rim diameter. That applies to the 155R13 radial fitment and the 560-13 bias-ply fitment, so the main rim question is not diameter but whether the wheel width matches the tire being considered.

That distinction matters because the available products do not all share the same rim-width range. Some 560-13 bias-ply tires suit narrower wheels, while 155R13 radial options are intended for a somewhat wider range. Measuring the actual wheel on the car is worthwhile, especially if the GT6 has replacement steel wheels, aftermarket wheels, or an older wheel set with uncertain specifications.

The 1971 Triumph GT6 Base is associated with the same two primary sizes used for the model overall: 155R13 in radial construction and 560-13 in bias-ply construction. That means tire selection does not hinge on a separate sub-model size difference within the covered GT6 fitment.

Even with shared sizing, the real decision is still important. The buyer should confirm whether the car is being kept in a period-style bias-ply format or set up around the radial size, then compare wheel width and appearance preferences. On a compact car like the GT6, small differences in tire construction and profile can noticeably affect both the look and the way the car feels on the road.

On the 1971 Triumph GT6, 560-13 is a numeric bias-ply tire size. It uses the older inch-based sizing system common on many vintage cars and differs from the GT6’s 155R13 radial fitment, which uses a metric radial format on the same 13-inch rim diameter.

That difference affects more than the label on the sidewall. A 560-13 bias-ply tire supports a more traditional period-style presentation, while the radial alternative moves the car into a different construction type. Before switching, it is smart to verify the wheel width on the car and compare the intended tire with the GT6’s available clearance, especially if the car no longer wears its original wheel setup.

Radial equivalents for 560-13 include 155R13 as the 80-series metric radial option, P155/75R13 as the 75-series P-metric alternative, and P155/70R13 as the 70-series P-metric alternative. A bias-look radial equivalent is not present for this size, so the radial path centers on these metric and P-metric formats.

Those equivalents are useful comparison points, not automatic substitutions. The recommended rim-width range attached to the radial-equivalent group is 4 to 5 inches, and the actual wheel on the car should be checked before converting. It is also worth confirming tire clearance and the car’s current ride height, since even narrow vintage sizes can behave differently once the construction and sizing format change.

The right choice depends on the role of the car. A 560-13 bias-ply tire keeps the GT6 in a more traditional vintage format, while a 155R13 radial follows the radial fitment associated with this model and stays within the same 13-inch wheel family.

Owners focused on restoration-oriented appearance often begin with the bias-ply size, especially when whitewall styling is part of the look they want. A driver-oriented car may lead toward the radial size instead. Either direction should be checked against the wheel width actually on the car, because the available bias-ply and radial products do not share the same rim-width specifications.

Start with the correct primary size and construction for the way the GT6 is set up now: 560-13 for bias-ply or 155R13 for radial. From there, compare wheel-width compatibility, brand, tire series, sidewall style, and any useful load or weight differences among the available products.

The most important mistake to avoid is treating every 13-inch tire as interchangeable. A narrow British sports coupe responds noticeably to tire construction, and the available products are built for different rim-width ranges. Choosing carefully means matching the car’s current wheels and intended appearance, then making sure the selected tire supports the kind of road use the GT6 will actually see.

The sidewall choices for a 1971 Triumph GT6 depend on the tire size and construction you choose. The 155R13 radial options are blackwall tires, while the 560-13 bias-ply range includes narrow whitewall and wide whitewall styles from BFGoodrich and Firestone.

That makes sidewall treatment part of the larger decision about how the car should present. Blackwall radials suit a cleaner sporting look, while whitewall bias-ply tires create a more traditional vintage appearance. Sidewall style should be chosen only after the correct size and wheel compatibility are confirmed, since appearance alone does not determine whether a tire is appropriate for the GT6’s actual setup.

The 1971 Triumph GT6 has tire options from Michelin, Dunlop, BFGoodrich, and Firestone. Michelin and Dunlop cover the 155R13 radial fitment, while BFGoodrich and Firestone supply the 560-13 bias-ply choices in classic-style lines with different sidewall presentations.

Brand matters mainly as part of the overall package rather than as a ranking exercise. Some buyers will be comparing radial blackwall tires in series such as Michelin XAS-FF or SP Sport Aquajet, while others will be looking at Silvertown Classic Bias Ply or Firestone Classic Bias Ply offerings. The smarter comparison is size, construction, wheel compatibility, and appearance, then the brand within that narrowed group.

For a period-style 1971 Triumph GT6, the 560-13 bias-ply size is the natural starting point because it preserves the vintage numeric format used on the car. Available bias-ply choices include BFGoodrich and Firestone tires with narrow whitewall and wide whitewall sidewall treatments.

That does not automatically make one whitewall treatment historically exact for every car. A restoration-oriented buyer should choose first by correct size and construction, then by the presentation that matches the vehicle’s intended era feel. When absolute originality matters, marque-club references, period photography, and vehicle-specific historical documentation can help narrow down the sidewall style that best suits a particular GT6.

Tire construction changes the visual character of a restored 1971 Triumph GT6 because 560-13 bias-ply and 155R13 radial tires come from different sizing traditions. The bias-ply size gives the car a more overtly vintage presentation, while the radial size keeps a narrow European look but reads as a later construction style.

That visual difference matters on a GT6 because the car is small, low, and strongly shaped by wheel-and-tire proportion. A restoration focused on traditional appearance may lean toward bias-ply, especially with a whitewall treatment, while a more driver-oriented restoration may prefer blackwall radials. The final choice should still be grounded in the wheel width on the car and the overall look the restoration is trying to achieve.

Yes, modifications can affect tire fitment on a 1971 Triumph GT6 even when the tire size itself is correct. Aftermarket wheels, changes in wheel width, suspension alterations, ride-height changes, or bodywork differences can all influence whether a 155R13 or 560-13 setup has proper clearance.

A GT6 is compact enough that small changes can matter. The safest approach is to verify the actual wheel dimensions on the car, then check steering clearance, fender clearance, and suspension travel before settling on a tire. That is especially important when moving between bias-ply and radial construction, since the tire may not behave the same way in service even on the same nominal rim diameter.

Before driving a 1971 Triumph GT6 on new tires, inspect the wheels for damage or excessive corrosion, confirm that the tire size and rim diameter match, and make sure inflation is set correctly for the tire being installed. It is also wise to check that the valve stems, lug hardware, and wheel mounting surfaces are in sound condition.

A short test drive should include listening for rubbing and feeling for any vibration or pull that suggests a fitment or mechanical issue. Collector cars also deserve a quick look at steering and suspension wear before regular road use, because loose components can mask themselves as tire problems. Rechecking pressure and visible clearance after the first miles is a sensible final step.

Tires on a collector 1971 Triumph GT6 should be inspected regularly for cracking, flat spotting, cuts, bulges, uneven wear, and signs of air loss, even if the car is driven only occasionally. Low-use vintage cars can age their tires out before they wear them out, so condition matters as much as tread depth.

Storage habits make a real difference. Keeping the GT6 away from prolonged sunlight, heat, moisture, and ozone sources helps preserve the tires, and maintaining proper inflation reduces stress on the casing while the car sits. It also helps to move the car periodically or use appropriate storage practices so the tires are not left carrying the same load in the same position for long periods.