1974 Triumph Tire Fitment Guide

1974 Triumph vehicles use three sizes across two models. The Spitfire uses either 155R13 or 560-13, and both mount on 13-inch rims. The TR6 uses 185R15, which mounts on a 15-inch rim. Rim width ranges also differ by size: 155R13 products span 4.00 to 5.50 inches where published, 560-13 spans 3.50 to 4.50 inches depending on the tire, and 185R15 spans roughly 4.5 to 6.5 inches.

That means year and make alone are not enough for a final choice on a 1974 Triumph. Spitfire owners still need to decide between a radial and a bias-ply path on the same wheel diameter, while TR6 owners need the 15-inch radial size built for that model. Verifying the model and then comparing your actual wheel against the published rim-width range is the cleanest way to avoid a mismatch.

On a 1974 Triumph, 560-13 is a numeric bias-ply size. The 5.60 figure is the nominal section width in inches, and the 13 is the wheel diameter in inches. Unlike a modern metric radial code, it does not spell out an aspect ratio in the size itself, and the format is tied to older bias-ply sizing practice used during the period.

For a 1974 Triumph Spitfire, 560-13 points you toward a more traditional presentation, especially when paired with the available whitewall styles. It also means the tire should be matched to a wheel width appropriate for that size rather than treated as interchangeable with every 13-inch tire. If your goal is a more original restoration look, this is the Spitfire size most likely to align with that direction.

On a 1974 Triumph, both 155R13 and 185R15 are Euro-metric radial sizes. The first number is section width in millimeters, the R indicates radial construction, and the final number is the rim diameter in inches. In this older metric convention, the aspect ratio is not written into the code and is commonly treated as an 80-series profile unless the tire states otherwise.

The key difference is where each size belongs in the Triumph range. 155R13 is the Spitfire radial option on a 13-inch wheel, while 185R15 is the TR6 radial size on a 15-inch wheel. Seeing the R in the size code also helps distinguish these from the Spitfire's 560-13 bias-ply option, which brings a different look and driving feel even before sidewall style enters the conversation.

If your 1974 Triumph is a Spitfire, both sizes belong to that model, but they serve different goals. The 155R13 is a radial in a later-style metric format, while the 560-13 is a numeric bias-ply size. That makes the decision less about basic model fitment and more about whether you want a more period-oriented presentation or a more modern radial driving character on the same 13-inch wheel diameter.

Owners restoring a Spitfire for a traditional look often lean toward 560-13, especially with the available whitewall treatments. Owners who expect more regular road use often prefer the radial route in 155R13, particularly since the available tires are H-rated and blackwall. Either way, start by checking your wheel width, because the published rim-width ranges are different between the two Spitfire sizes.

Sidewall style varies noticeably across 1974 Triumph tire sizes. The Spitfire's 155R13 radial choices are blackwall only, while its 560-13 bias-ply choices come in narrow whitewall and wide whitewall form. The TR6's 185R15 radial offerings cover blackwall, narrow whitewall, and redline, giving that model the widest visual range within the year.

For a 1974 British sports car, blackwall is usually the most neutral and broadly appropriate visual choice, especially on a driver. Whitewall and redline choices are more about the specific look you want the car to project. If show authenticity matters, compare the sidewall style to period photos, sales literature, and marque-club guidance for your exact market version rather than choosing purely by appearance.

Four brands cover 1974 Triumph fitments across the three sizes: Michelin, Dunlop, BFGoodrich, Firestone, and Coker Classic. The 155R13 Spitfire radial size is available from Michelin and Dunlop. The 560-13 Spitfire bias-ply size comes from BFGoodrich and Firestone. The 185R15 TR6 radial size is available from Coker Classic and Michelin.

Brand choice on a 1974 Triumph is best approached size by size rather than make-wide. A Spitfire owner comparing 155R13 is really deciding between two radial interpretations, while a TR6 owner in 185R15 can also choose among different sidewall treatments and speed ratings. Once the correct size is settled, the next useful comparison is sidewall style, tube marking, and any published speed or load information for the specific tire.

Rim-width guidance for 1974 Triumph tires depends on the size. In 155R13, published fitments run from 4.00 to 5.50 inches where stated. In 560-13, the range runs from 3.50 to 4.50 inches depending on brand and sidewall version. In 185R15, published ranges span about 4.5 to 6.5 inches, with some tires beginning at 5.00 inches and others covering slightly narrower wheels.

That spread is wide enough that wheel measurement matters before purchase, especially on older British sports cars that may have had wheels changed over the years. A 13-inch wheel alone does not guarantee that both Spitfire sizes are equally appropriate on your exact rim width. Measure the wheel, compare it to the intended size's range, and treat brand-specific fitment notes as part of the final decision.

Inner-tube requirements on 1974 Triumph tires vary by size and sometimes by the individual product. The Michelin 155HR13 and Michelin 185HR15 and 185VR15 tires are marked TL, indicating tubeless construction. Other products in 155R13 and 185R15 do not all carry the same marking in the size description, so tube status varies by product across those sizes. The 560-13 bias-ply products do not use a uniform tube marking in the product naming.

On an older Triumph, the wheel itself matters just as much as the tire marking, because original wheel design and condition can influence whether tubeless use is appropriate. If you are fitting original or restored wheels, confirm both the tire's sidewall marking and the wheel's suitability before mounting. That is especially important when switching between older-style tires and later radial constructions on a vintage sports car.

A 1974 Triumph should be stored in a cool, dry space away from direct sunlight, electric motors, battery chargers, furnaces, and other ozone sources that age rubber. Keep the tires clean, maintain inflation, and move the car periodically so one section of tread and sidewall is not carrying the load for months at a time. Bias-ply tires such as the Spitfire's 560-13 are more prone to flat-spotting during long static storage than the radial sizes used elsewhere in the range.

If the car will sit for an extended period, owners often use tire cradles or stands to reduce stress at the contact patch. That can be especially helpful on lightweight sports cars that are stored for a season at a time and then expected to drive smoothly right away. A simple storage routine does more to preserve ride quality and sidewall condition than occasional low-mileage use alone.

On a 1974 Triumph, tire life is usually judged more by age and condition than by mileage. Collector-car tires often look usable long after the rubber has begun to harden, so a careful evaluation at about five to seven years is wise, with replacement commonly considered by around ten years regardless of tread depth. The DOT date code and the tire's storage history matter at least as much as miles driven.

That is especially true for hobby cars like a Spitfire or TR6 that may spend much of the year parked and then be driven spiritedly on fair-weather outings. Sidewall checking, vibration, loss of wet-weather confidence, and persistent pressure loss are all stronger warning signs than a worn tread pattern alone. Age-out planning is one of the most sensible maintenance habits on a vintage Triumph.

Tires on a 1974 Triumph should be checked before every drive and more thoroughly before any longer outing. Look for sidewall cracking, cuts, bulges, uneven wear, lodged debris, and any change in how well the tire holds pressure. If your setup uses tube-type components or older valve hardware, include the valve stems and any signs of tube-related leakage in that inspection routine.

A short walk-around matters on a classic British sports car because long idle periods can hide problems that are not obvious until the car is rolling. It is far better to catch a cracked sidewall or soft tire in the garage than on a two-lane road or interstate shoulder. Pair the tire check with a quick look at wheel fasteners, fluid leaks, and brake feel before heading out.

For a 1974 Triumph Spitfire, both the period-correct construction story and the model's market timing matter. Bias-ply tires remained a traditional fitment style in earlier decades, while radial use had become firmly established by the 1970s on many sports cars, especially in European applications. Within current Spitfire coverage, the model is served by both 560-13 bias-ply and 155R13 radial sizes, reflecting the two restoration directions owners commonly consider.

If originality is your goal, treat the exact factory fitment as something to confirm against a handbook, factory literature, or a Triumph marque club for your specific market version. Construction type, sidewall treatment, and overall look can all affect how authentic the car appears. The safest approach is to verify what your car would have worn new, then choose the closest modern reproduction in that same general format.

Correct tire fitment can matter a great deal when showing a 1974 Triumph, particularly in judged classes that emphasize factory-correct presentation. Size, construction type, and sidewall style are all visible cues, and judges familiar with the model will notice if a car wears a modern-looking radial where a period-style tire would be more appropriate, or a sidewall treatment that looks out of character for the car's market and era.

That does not mean every show car needs the same tire, because standards vary between local events, marque meets, and high-level concours judging. A Spitfire built as a driver may reasonably wear a radial, while a tightly restored example may call for a different visual approach. Before making a final choice, compare your target event's judging priorities with advice from Triumph clubs and period reference material.

On the 1974 Triumph TR6, Michelin XVS and Coker Classic Radial both appear in 185R15, but they differ in presentation and published specifications. Coker Classic offers a redline version with a 1355-pound load figure at 35 psi, while Michelin XVS appears in blackwall and narrow whitewall form. Michelin also brings more than one speed rating within the size, with H-rated versions to 130 mph and a V-rated version to 149 mph.

That means the choice is not simply one brand versus another. A TR6 owner can prioritize visual character, compare rim-width ranges, and then decide whether the published speed category matters for the car's intended use. If you are restoring toward a specific period appearance, the sidewall treatment may drive the choice; if you are building a road car, you may focus more on the exact spec spread within the 185R15 offerings.

1974 Triumph tires can be suitable for highway driving when they are in good condition, correctly mounted, and used within their stated speed category. The radial choices carry H and V speed ratings where marked, which correspond to 130 mph and 149 mph ceilings, and those limits are well above normal U.S. highway speeds. The Spitfire's 560-13 bias-ply options do not present the same modern speed-marking detail, so they should be approached with the expectations appropriate to an older tire design.

In real-world driving, the car's own condition often matters more than the tire's published ceiling. Brake performance, steering play, suspension wear, and alignment can all shape how confident a 1974 Triumph feels at speed. If the car is mechanically sorted and the tires are fresh and correctly inflated, highway use is realistic; if not, no speed-rated tire will make up for age-related chassis or brake problems.

Inflation pressure on a 1974 Triumph should start with the vehicle manufacturer's recommendation for the exact model and tire type, then be checked against the tire's own published maximum load-and-pressure figure where one is given. The 560-13 bias-ply products show 850 pounds at 30 psi, and one 185R15 radial shows 1355 pounds at 35 psi. Those figures describe the tire's rated load relationship, not a universal setting to copy across all Triumph sizes.

Because the Spitfire and TR6 use different sizes, wheel widths, and constructions, pressure should never be transferred casually from one setup to another. A factory handbook, workshop literature, or marque specialist is the right source for the starting point on your model. Once you have that baseline, regular pressure checks matter more than chasing small changes, especially on a classic car that may sit between drives.

Before a longer drive in a 1974 Triumph, inspect each tire for cracking, bulges, cuts, embedded objects, uneven wear, and proper cold inflation. Check the valve stems, confirm the spare is usable, and make sure the wheel hardware is secure. If your car uses tube-type components or older wheels, include those details in the pre-trip review rather than assuming a recently mounted tire is automatically ready for distance use.

A longer outing in a vintage British sports car also calls for a quick broader mechanical check. Brake feel, coolant level, charging behavior, lights, and fluid leaks deserve attention before the tires ever touch the road. Tires are only one part of the readiness picture, but they are the part you can inspect visually in a few minutes, and that makes them the easiest place to catch trouble early.