1978 Triumph Tire Fitment Guide

1978 Triumph vehicles use four distinct tire sizes across three models. The Spitfire uses 155R13 and 560-13, the TR7 uses 185/70R13 and 185R13, and the TR8 uses 185/70R13. Every size in this year and make mounts on a 13-inch rim, but the tire widths and construction types are not the same. Rim-width ranges where published run from 3.50-4.50 inches for 560-13, 4.00-5.50 inches for 155R13, and roughly 4.5-6.5 inches for 185/70R13.

That means a 1978 Triumph buyer needs to identify the model first, not just the year and make. A Spitfire owner is choosing between a small radial and a traditional numeric bias-ply, while a TR7 owner may need to distinguish between a 70-series radial and a taller-profile 185R13 radial. Shared 13-inch wheel diameter helps simplify the conversation, but section width and approved rim-width range still need to match the actual wheel before ordering.

On a 1978 Triumph, 560-13 is a numeric bias-ply size. The 560 portion is the nominal section-width designation in older domestic-style sizing, and the 13 is the wheel diameter in inches. That format does not include a modern metric width or aspect-ratio expression, because it belongs to an earlier sizing system that was common before radial metric markings became standard.

For a 1978 Triumph Spitfire owner, 560-13 signals a traditional bias-ply replacement rather than a modern-style radial. It is the size to focus on when the goal is classic appearance and a more period-authentic presentation, especially with the whitewall options that exist in this fitment. Before choosing one, verify that your wheels fall within the approved rim-width range for the exact tire, since published ranges differ slightly by product.

No, 1978 Triumph models do not all use the same tire size. The Spitfire uses 155R13 and 560-13, the TR7 uses 185/70R13 and 185R13, and the TR8 uses 185/70R13 only. All of them stay with a 13-inch rim diameter, but the width, profile, and in one case the construction type differ from model to model.

That difference matters because the tire decision changes with the car. A Spitfire owner may be deciding between bias-ply authenticity and a metric radial alternative, while TR7 and TR8 owners are sorting among radial sizes with different overall proportions and product styles. If you are working from an inherited car, a long-stored project, or a vehicle with aftermarket wheels, check the sidewall marking on the current tires and the wheel itself before settling on a replacement size.

For a 1978 Triumph Spitfire, the choice between 155R13 and 560-13 is mainly a construction and presentation decision. The 155R13 is a radial metric size offered in blackwall form, while the 560-13 is a numeric bias-ply available with narrow or wide whitewall styling. Both fit the Spitfire model family, but they deliver a different era feel and visual character.

A Spitfire aimed at show presentation or a traditional restoration usually points buyers toward the 560-13 bias-ply route. A Spitfire expected to see more casual road use often leads owners toward the 155R13 radial because it keeps the car in a radial format without changing wheel diameter. The best first step is to decide whether your priority is original-style appearance or a more contemporary radial driving experience, then confirm the wheel width for the exact tire.

1978 Triumph tire choices span several sidewall looks depending on size. The 155R13 and 185R13 options are blackwall only, 560-13 comes in narrow whitewall and wide whitewall form, and 185/70R13 is available as blackwall, redline, and wide whitewall. That gives Triumph owners a wider cosmetic spread than many single-size import applications from the period.

For most late-1970s British sports-car restorations, blackwall is the most natural visual direction, especially on TR7 and TR8 applications. Whitewall and redline alternatives can still be useful when the owner is chasing a specific custom look or a personalized period vibe rather than strict factory-style presentation. Because the sidewall treatment can change the personality of the car as much as the tread construction, it helps to choose the appearance standard before narrowing down brand and series.

1978 Triumph fitments are covered by Michelin, Dunlop, BFGoodrich, Firestone, and Avon. Michelin and Dunlop appear in 155R13, BFGoodrich and Firestone cover 560-13, BFGoodrich, Avon, and Dunlop appear in 185/70R13, and Michelin covers 185R13. That spread gives buyers access to both heritage-focused names and reproduction-oriented specialty offerings across the year’s different models.

Brand choice usually comes after the size decision, because each Triumph model narrows the field quickly. A Spitfire owner choosing bias-ply is looking at BFGoodrich or Firestone, while a TR7 or TR8 owner shopping 185/70R13 has a broader mix of styling and speed-rating possibilities. Once you know the correct size, compare brands by sidewall appearance, rim-width compatibility, and whether you want a touring-oriented or sportier period presentation.

Rim-width requirements vary by tire size on 1978 Triumph vehicles. The 560-13 bias-ply size works across published ranges from 3.50-4.50 inches depending on the exact product, the 155R13 radial uses 4.00-5.50-inch rims where a range is published, and 185/70R13 radial products span about 4.5-6.5 inches. Every one of these fitments uses a 13-inch rim diameter, but width compatibility broadens as the tire gets larger.

That makes wheel measurement worth doing before you settle on a tire, especially if the car has had wheel changes during its life. A Spitfire on narrow original wheels may be ideal for the smaller sizes, while a TR7 or TR8 on a wider 13-inch wheel can support the broader 185-section tires more comfortably. The safest path is to confirm the actual wheel width at the bead seat and match it to the exact tire’s approved range.

Most 1978 Triumph tire choices here are radial products, and some are clearly marked tubeless. The 155R13 Michelin and 185R13 Michelin carry TL markings, while the 560-13 bias-ply and several other radial products do not use a tube designation in the size marking. Because tube marking is not uniform across every product, tube requirements can vary by product and by the wheel you are using.

The practical step is to treat the wheel and tire as a system rather than making a blanket assumption from size alone. Original wheel design, wheel condition, and the exact tire construction all matter, especially on an older sports car that may have been restored or modified. If your wheel is an original-style rim and you are considering a bias-ply tire, confirm tube guidance with the tire manufacturer and inspect the wheel carefully before final installation.

All 1978 Triumph tire sizes in this group fit 13-inch wheels, so there is shared rim diameter across the Spitfire, TR7, and TR8 families. That does not mean every original wheel is automatically suitable for every size, because the approved rim-width ranges differ substantially between the smaller Spitfire sizes and the wider 185-section TR7 and TR8 fitments.

A Spitfire wheel narrow enough for 560-13 is not the same setup as a TR7 or TR8 wheel intended for 185/70R13. The shared 13-inch diameter simply tells you the tire can mount on the same nominal rim diameter, not that it belongs on every 1978 Triumph wheel. If you are moving between sizes or using replacement wheels, confirm actual wheel width first and keep the tire matched to the model the wheel was built to support.

A stored 1978 Triumph should be kept out of direct sunlight, away from ozone-producing equipment such as electric motors and compressors, and on a clean, dry surface. Tire pressure should be maintained during storage, and the car should be rolled periodically or supported in a way that reduces prolonged stress on one contact patch. Bias-ply tires such as 560-13 are generally more prone to flat-spotting during long static storage than radial designs.

That matters especially with a collector British sports car that may spend long stretches parked between events or seasonal drives. A Spitfire on bias-ply tires deserves extra care to prevent shape memory and casing stress, while a TR7 or TR8 on radials still benefits from pressure checks and movement during storage. Keep petroleum products off the sidewalls, and use breathable covers rather than plastic wraps that can trap moisture around the tire and wheel.

Tires on a 1978 Triumph are usually judged more by age than by tread wear, because many collector cars cover limited annual mileage. A sensible rule is to begin evaluating tires closely once they are around five to seven years old and to consider replacement around ten years regardless of remaining tread. The DOT date code on the tire is the key reference point for age, even if the tread still looks healthy.

That approach is especially important on lightly used sports cars that may appear road-ready after long periods of storage. A tire can retain usable-looking tread while the rubber hardens, cracks, or loses resilience with age. If your Triumph has recently come out of storage or has tires of uncertain age, inspect the date codes first and treat visible sidewall weathering, vibration, or persistent pressure loss as reasons to move replacement higher on the priority list.

Tires on a 1978 Triumph should be checked before every drive, with a more thorough inspection before any longer outing. Look for cracking, cuts, bulges, uneven wear, and pressure loss, and make sure the tread area is free of embedded damage. On wheels using tube-type-compatible setups or older valve hardware, stem condition and leakage deserve the same attention as the casing itself.

Frequent inspection matters because small vintage sports cars communicate tire issues quickly, but they also tend to sit long enough for age-related problems to develop between drives. A quick visual check before leaving the garage can catch sidewall cracking or a soft tire before it becomes a road problem. Before a tour or highway run, add a pressure check and a spare-tire inspection so the whole package is ready, not just the four tires on the ground.

A 1978 Triumph Spitfire sits in an era when radial tires were widely established, but traditional replacement culture still preserved older-style fitments for restoration and appearance goals. Within this year and make, the Spitfire is supported by both 155R13 radial and 560-13 bias-ply options. That means a buyer can approach the car from either a late-period radial standpoint or a more classic bias-ply presentation, depending on how the individual car is being restored or judged.

For a factory-authentic answer on a specific market car, trim package, or delivery region, a Triumph marque club or original handbook is still the right final checkpoint. Imported British cars often changed subtly by market, and judges may care about sidewall style as much as size and construction. Use the size family as the first filter, then verify whether your restoration target calls for a blackwall radial look or a more traditional bias-ply appearance.

Correct tire fitment matters on a 1978 Triumph because judges and knowledgeable enthusiasts often notice size, construction, profile, and sidewall treatment immediately. A Spitfire wearing a modern-looking radial may present differently from one restored around a traditional bias-ply look, and a TR7 or TR8 with an incorrect sidewall treatment can alter the car’s period character just as quickly as an incorrect wheel finish.

What counts as correct depends on the event and the restoration standard you are chasing. Club-level shows may allow more flexibility, while stricter concours settings can be particular about whether the tire looks right for the year, market, and model. Before committing to a set, compare the tire’s construction and sidewall style to period photos, factory literature, and the standards used by the Triumph club or judging body relevant to your car.

For a 1978 Triumph Spitfire using 560-13, BFGoodrich and Firestone both offer bias-ply choices with the same 850-pound load rating at 30 psi, but they differ in styling and published rim-width range. BFGoodrich offers both a 1.00-inch narrow whitewall and a 2.25-inch wide whitewall on 3.50-4.00-inch rims, while Firestone offers a 2.25-inch wide whitewall on a 4.00-4.50-inch rim range.

That makes the decision partly visual and partly wheel-driven. If your Spitfire is built around a slimmer whitewall look, BFGoodrich is the route that provides it, while a buyer wanting a wide whitewall can compare brand preference and wheel width before choosing. On a narrow wheel, the BFGoodrich range may align more naturally; on a slightly wider wheel, the Firestone fitment window can be the better match.

1978 Triumph tires can be suitable for highway driving when the correct size, condition, and speed rating are matched to the car. H-rated examples in 155R13, 185/70R13, and 185R13 carry a 130 mph ceiling, while the Dunlop 185/70VR13 carries a V rating with a 149 mph ceiling. The 560-13 bias-ply fitment does not carry the same modern speed-letter presentation, so its road character should be approached with the expectations appropriate to a vintage-style tire.

In real use, the limiting factor on a 1978 Triumph is often the age and condition of the vehicle itself rather than the tire’s headline speed ceiling. Brakes, suspension, steering components, and alignment all matter on small British sports cars, especially after long storage. For normal highway use, the smarter question is whether the tires are fresh, properly inflated, and appropriate to the model, not whether the speed rating exceeds what the car will realistically see.

Inflation pressure on a 1978 Triumph should follow the vehicle manufacturer’s recommendation first, then be checked against the tire maker’s own maximum-load-and-pressure marking for the specific size. The 560-13 bias-ply examples carry 850 pounds at 30 psi, and the 185/70R13 BFGoodrich radial examples carry 1,135 pounds at 35 psi; the Dunlop 185/70VR13 shows 1,047 pounds in that size. Those figures describe the tire’s rated load point, not a universal setting for every 1978 Triumph.

Because the Spitfire, TR7, and TR8 differ in weight, balance, and intended use, pressure should not be transferred casually from one model or tire size to another. Start with the factory recommendation for your exact model, then make sure it remains within the tire manufacturer’s acceptable operating range. If the car has non-original wheels, suspension changes, or a different size than it wore previously, revisit pressure setup carefully rather than assuming the old number still applies.

Before a longer drive in a 1978 Triumph, inspect all four tires and the spare for age cracking, tread separation, cuts, bulges, and correct cold pressure. Confirm that the valve stems are sound, and pay close attention to any wheel-and-tire combination that has been sitting for months because pressure loss and flat-spotting can develop quietly in storage. If the car uses an older-style or tube-compatible setup, stem and sealing condition deserve extra scrutiny.

Tires are only one part of the pre-trip routine on a late-1970s Triumph. A longer run also calls for checking wheel fasteners, fluid levels, cooling health, and the condition of suspension and steering parts that influence how the tire actually behaves on the road. When the tire size, pressure, and wheel match are all sorted before departure, the car is far more likely to drive as intended and far less likely to surprise you miles from home.