1968 Jaguar 340 Tires

A 1968 Jaguar 340 uses two primary tire sizes: 185R15 in radial construction and 640-15 in bias-ply construction. Both are 15-inch fitments, so the difference is not wheel diameter alone but the overall tire format and construction choice on the car.

That means the first decision is whether the Jaguar is being kept in a traditional bias-ply setup or equipped with a radial. After that, compare the tire against the car’s actual wheel width, sidewall style preference, and any changes that may have been made over the years, especially on collector cars that no longer wear their original wheel and tire combination.

The 1968 Jaguar 340 uses a 15-inch rim with both of its primary tire sizes, 185R15 and 640-15. Even though the tire constructions differ, the shared rim diameter keeps the tire decision centered on bias-ply versus radial rather than on changing to a different wheel diameter.

Rim diameter is only part of the fitment picture, so wheel width still needs attention before choosing a tire. That is especially important if the car has alloy wheels, aftermarket wheels, or older replacement wheels, because a tire can match the 15-inch diameter and still require closer checking for width compatibility and overall clearance.

Yes. Both the 1968 Jaguar 340 Sedan and the 1968 Jaguar 340 Sedan w/alloy wheels use the same two primary size paths: 185R15 radial and 640-15 bias-ply. The covered sub-models do not split into different tire diameters or unique size-only fitments.

That makes sub-model identification less about finding a different size and more about confirming the car’s current wheel setup. A sedan with alloy wheels may still warrant a closer look at wheel width and tire profile before moving between bias-ply and radial options, especially if originality, stance, or clearance is part of the buying decision.

640-15 is a bias-ply tire size for the 1968 Jaguar 340. It uses the older numeric bias-ply sizing format, and it represents the traditional construction choice among the model’s two primary fitment paths alongside the radial 185R15 option.

Choosing 640-15 usually points toward a more vintage appearance and feel, especially because this size is available in blackwall, narrow-whitewall, and wide-whitewall versions. Before selecting one, verify that the car’s current 15-inch wheels match the tire’s intended rim-width range and that the rest of the suspension and steering setup remains suitable for a bias-ply configuration.

Radial equivalents for 640-15 include 175R15, P175/75R15, and P185/70R15. Those represent three different radial sizing conventions: an 80-series metric radial, a P-metric 75-series radial, and a P-metric 70-series radial for owners comparing modernized alternatives to the original bias-ply format.

Each of those sizes should be treated as an alternative to evaluate rather than an automatic substitute. A 5-6 inch rim-width range is associated with the equivalent fitment path, so wheel width, overall tire dimensions, and body or steering clearance should be confirmed carefully before converting a 1968 Jaguar 340 from 640-15 bias-ply tires.

Start by confirming which bias-ply size the car is using and which radial size is being considered in its place. For a 640-15 fitment, the available radial-equivalent choices are 175R15, P175/75R15, and P185/70R15, while 185R15 is also a primary radial fitment used on the 1968 Jaguar 340.

The practical checks are wheel diameter, wheel width, and available clearance through the steering range and suspension travel. It also helps to inspect the condition of the wheels and suspension before making the change, because an older collector car may have worn bushings, tired springs, or non-original wheels that affect how a radial setup sits and behaves.

Begin with the two main fitment directions: 640-15 bias-ply or 185R15 radial. That choice shapes the car’s appearance and setup more than brand alone, because it determines whether the Jaguar is staying with a traditional bias-ply format or moving into a radial tire profile on the same 15-inch rim diameter.

After the size path is settled, compare sidewall presentation, tire series, and wheel-width compatibility. The available range includes blackwall, redline, narrow-whitewall, and wide-whitewall styles, so the right tire often depends on whether the car is being prepared for restoration-oriented presentation, regular road use, or a balance between period style and modern radial construction.

The 1968 Jaguar 340 has a broad sidewall selection across its available tire sizes. Depending on the size and series chosen, options include blackwall, redline, narrow whitewall, and wide whitewall, giving the car noticeably different visual character even when staying within a correct 15-inch fitment family.

Sidewall style is one of the most visible choices on a classic saloon, so it should match the look you want before comparing brands or series. Wide whitewalls tend to emphasize a more formal vintage presentation, while blackwalls and redlines create a sportier or more understated look, especially when paired with the radial 185R15 offerings.

Tires for the 1968 Jaguar 340 are available from several brands, including Michelin, Avon, Coker Classic, Universal Vintage Tire, Firestone, BFGoodrich, and Excelsior. Those brands appear across the two primary size paths, so the brand conversation is tied closely to whether the car is staying with 640-15 bias-ply or moving to 185R15 radial.

Brand should be compared alongside the tire series, sidewall treatment, and wheel specifications rather than by name alone. A Michelin or Avon radial may suit one type of Jaguar road-use plan, while Firestone, BFGoodrich, or Excelsior bias-ply options may better support a restoration-oriented appearance with blackwall or whitewall styling.

A period-style 1968 Jaguar 340 usually starts with deciding whether the car should wear the traditional 640-15 bias-ply size or the 185R15 radial size. The bias-ply route leans more heavily into vintage presentation, while the radial route can still preserve a classic look depending on the sidewall and series selected.

Appearance details matter as much as size, especially on a British sporting saloon where whitewall width, blackwall presentation, or a redline can change the car’s character quickly. When exact originality is important, verify historical references specific to the car before settling on a brand or sidewall treatment, since period-style and factory-delivered are not always the same thing.

Tire construction changes the visual stance of a restored 1968 Jaguar 340 as much as it changes the driving setup. A 640-15 bias-ply gives the car a more traditional vintage presentation, while a 185R15 radial introduces a later-style radial look even though both remain 15-inch fitments.

That visual difference becomes more pronounced once sidewall style enters the decision. A wide-whitewall bias-ply can create a formal, distinctly period look, while blackwall or redline radial options can make the same Jaguar appear more sporting and road-focused. The better choice depends on whether the restoration goal is traditional presence, subtle modernization, or a balanced collector-driver approach.

Yes. Modifications can affect tire fitment on a 1968 Jaguar 340 even when the tire size itself is correct. Changes such as aftermarket wheels, different wheel widths, altered ride height, suspension work, or body clearance differences can all influence how a 640-15 or 185R15 tire sits and clears the car.

That matters most when moving between bias-ply and radial setups or when the car has alloy wheels that may not match a standard steel-wheel specification. Before installing new tires, check the actual wheel dimensions and inspect clearance at full steering lock and through normal suspension movement so the chosen tire works with the car as it exists today.

Before driving a 1968 Jaguar 340 on new tires, inspect the wheels for condition and correct diameter, then look over the suspension and steering for looseness or visible wear. It also helps to confirm proper inflation, make sure each tire seats correctly, and check for any immediate interference once the car is back on the ground.

Collector cars often spend long periods parked, so the tire installation is a good time to examine brake condition, wheel fastener security, and any signs of rubbing inside the wheel openings. A short, careful road test can reveal pull, vibration, or clearance issues early, which is especially useful when the Jaguar has changed from one construction type to another.

Tires on a collector 1968 Jaguar 340 should be maintained with regular pressure checks, periodic visual inspections, and careful storage habits. Even a lightly driven car can develop aging-related issues, so sidewall cracking, flat spotting, cuts, bulges, and unexplained air loss deserve attention whether the car wears 640-15 bias-ply tires or 185R15 radials.

Storage conditions make a real difference on seldom-driven classics. Keeping the Jaguar away from prolonged sunlight, excess heat, moisture, and ozone sources can help preserve the tires between drives, and rolling the car periodically can reduce long-term stress in one contact area. It is also wise to inspect tread and sidewalls before any longer outing rather than relying on mileage alone.