The 1968 Fiat 1800 reflects the practical European family-car thinking of its era, with tidy dimensions, understated styling, and the kind of road manners that made mid-century Italian sedans and wagons so appealing. Tire fitment on this model is not one-size-fits-all, because the Sedan and Wagon use different wheel diameters and can be found with either period bias-ply sizing or radial fitments. That makes the decision less about brand alone and more about confirming body style, wheel size, and whether the goal is a traditional look or a more modern radial driving setup. Sidewall presentation and tire series also matter, especially on a restoration-minded car.
Which Tire Size Is Right for The 1968 Fiat 1800
Four primary tire sizes apply to the 1968 Fiat 1800, and they are split by sub-model, construction, and rim diameter. The Sedan uses 15-inch tires, while the Wagon uses 14-inch tires, with both radial and bias-ply choices in their respective sizes. The first step is confirming whether the car is a B Sedan or a Wagon, then verifying the wheel diameter before choosing between a period-style bias-ply fitment and a radial alternative.
165R15 is a Euro-metric radial size in which 165 identifies the nominal section width in millimeters, R denotes radial construction, and 15 is the wheel diameter in inches. On the 1968 Fiat 1800, this size gives the B Sedan a radial fitment on a 15-inch rim and serves as the modern-style counterpart to the older 590-15 bias-ply format. Available choices include blackwall, narrow whitewall, and wide whitewall designs from brands such as Michelin, Vredestein, BFGoodrich, American Classic, Firestone, and Coker Classic. It suits buyers who want a 15-inch radial in a size that still feels appropriate to the car's period proportions.
590-15 is a numeric bias-ply size where 590 represents an approximate nominal section width of 5.90 inches and 15 identifies the wheel diameter. This is the traditional bias-ply fitment associated with the 15-inch-wheel Sedan configuration, making it especially relevant for buyers who want a more vintage construction and presentation. Product choices include blackwall and wide whitewall versions, with BFGoodrich and Avon represented across classic bias-ply series. It is the size to evaluate when period-style appearance and original-type construction matter more than moving to a later radial format.
175R14 is a Euro-metric radial size with a 175-millimeter nominal section width, radial construction, and a 14-inch rim diameter. On the 1968 Fiat 1800, this size belongs to the Wagon configuration, so it should not be confused with the Sedan's 15-inch fitments. Blackwall radial options are available from Michelin and Vredestein in series such as XAS, Sprint Plus, and Sprint Classic, giving the buyer a few distinct approaches within the same basic size. It is the right direction for Wagon owners keeping the 14-inch wheel setup and wanting a radial tire in the proper format.
6.40-14 is a numeric bias-ply size in which 6.40 indicates nominal section width in inches and 14 refers to the wheel diameter. This size corresponds to the Wagon's 14-inch bias-ply fitment and represents the more traditional construction choice for that sub-model. The size itself is useful to buyers who are preserving a vintage driving character and visual stance rather than converting the Wagon to a radial alternative. Before selecting it, confirm that the car still carries the correct 14-inch wheels and has not been changed to a different diameter during past restoration or service work.
Sub-model matters on the 1968 Fiat 1800 because the B Sedan and Wagon do not share the same tire size or wheel diameter. Confirming the exact body style is the quickest way to narrow the choice between 15-inch Sedan fitments and 14-inch Wagon fitments, along with the matching bias-ply and radial options.
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1968 Fiat 1800 B Sedan
The 1968 Fiat 1800 B Sedan uses 15-inch tire fitments, with a choice between 165R15 radial and 590-15 bias-ply sizing. That gives Sedan owners a clear decision between retaining a more traditional construction or choosing a radial in the same wheel diameter, along with several sidewall and tire-series options in 165R15.
The 1968 Fiat 1800 Wagon uses 14-inch tire fitments rather than the Sedan's 15-inch setup, with 175R14 radial and 6.40-14 bias-ply sizes associated with this body style. Tire selection starts with confirming that 14-inch wheel diameter, then deciding whether the goal is a vintage bias-ply look or a radial presentation for road use.
Bias-Ply to Radial Tire Conversion for the 1968 Fiat 1800
For the original 590-15 size, three radial-equivalent options are available. 165R15 is the 80-series metric radial equivalent, P165/75R15 is the P-metric 75-series radial equivalent, and P175/70R15 is the P-metric 70-series radial equivalent. These choices move from a classic Euro-metric format to lower-profile P-metric alternatives, while 590-15 itself remains the primary bias-ply size. A recommended rim-width range of 4 to 5 inches applies when evaluating these alternatives, and wheel size, overall dimensions, and vehicle clearance should still be checked before conversion.
Modern Radial Equivalents
165R15
Equivalent 80-series Metric Radial (590-15)
P165/75R15
Equivalent P-metric 75-series Radial (590-15)
P175/70R15
Equivalent P-metric 70-series Radial (590-15)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (4-5 in) and load needs match your vehicle specifications.
Check fender clearance, steering clearance, and stance before installation.
Consider suspension condition and intended road use when choosing equivalents.
Important Fitment Notes
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Best 1968 Fiat 1800 Tires for Sale
Available 1968 Fiat 1800 tire choices span radial and bias-ply constructions, with brands including Michelin, Vredestein, BFGoodrich, Firestone, American Classic, Coker Classic, and Avon. Buyers can compare blackwall, narrow whitewall, and wide whitewall styles across several tire series, especially in the Sedan's 165R15 and 590-15 sizes.
Owners researching 1968 Fiat 1800 tires usually need to sort out sub-model fitment first, then compare 14-inch versus 15-inch wheels, bias-ply versus radial construction, and the available sidewall and product choices. These answers focus on the exact sizes used on the Sedan and Wagon.
Tire Size & Fitment
What tire size fits a 1968 Fiat 1800?
The 1968 Fiat 1800 uses more than one primary tire size. The B Sedan uses 165R15 in radial form or 590-15 in bias-ply form, while the Wagon uses 175R14 in radial form or 6.40-14 in bias-ply form. Those sizes are tied to different wheel diameters and body styles.
The practical first step is identifying whether the car is a B Sedan or a Wagon, then confirming whether it still has 15-inch or 14-inch wheels. Many older cars have been changed over the years, so body style alone should not replace a quick wheel check before selecting a tire.
What size rim does a 1968 Fiat 1800 use?
A 1968 Fiat 1800 can use either a 15-inch rim or a 14-inch rim, depending on the sub-model. The B Sedan is associated with 15-inch tire sizes, while the Wagon is associated with 14-inch tire sizes. That difference is central to choosing the correct tire.
Wheel diameter should be confirmed before looking at brands or sidewall styles, because a 14-inch tire and a 15-inch tire are not interchangeable. On collector cars, it is also smart to verify the actual wheel width and make sure the current wheels match the tire size being considered.
Why does the 1968 Fiat 1800 have more than one tire size?
The 1968 Fiat 1800 has more than one tire size because fitment changes by sub-model and by construction type. The Sedan and Wagon use different rim diameters, and each of those setups can appear in either a traditional bias-ply size or a radial size. That creates four primary fitment paths across the model line.
For a buyer, that means tire selection starts with configuration, not with appearance or brand preference. Once the correct body style and wheel diameter are confirmed, the remaining decision becomes whether to stay with a period-style bias-ply tire or move to the radial size used on that same sub-model.
Bias-Ply & Radial Options
Is 590-15 a bias-ply or radial tire for the 1968 Fiat 1800?
590-15 is a bias-ply tire size on the 1968 Fiat 1800 B Sedan. It is the traditional numeric bias-ply fitment on a 15-inch rim, while 165R15 is the radial size associated with the same Sedan wheel diameter. The two sizes represent different construction approaches on that sub-model.
That distinction matters because the choice affects both appearance and the type of tire you are shopping for. A buyer considering 590-15 should also confirm that the wheel setup still matches the narrower rim requirements commonly associated with this older bias-ply size before making a final selection.
What radial tire sizes are equivalent to 590-15?
Radial equivalents for 590-15 include 165R15 as the 80-series metric radial option, P165/75R15 as the 75-series P-metric option, and P175/70R15 as the 70-series P-metric option. These are equivalent-size alternatives for the 15-inch Sedan fitment rather than additional primary sizes for every 1968 Fiat 1800 configuration.
A recommended rim-width range of 4 to 5 inches is part of that comparison, which makes wheel confirmation especially important before changing construction or sizing format. Tire diameter, section width, and clearance at the fenders and steering components should also be checked rather than assuming any equivalent will automatically work.
What should I check before converting my 1968 Fiat 1800 from bias-ply to radial tires?
Start by confirming the exact sub-model and wheel diameter, because the Sedan and Wagon do not use the same rim size. For a Sedan with the original 590-15 bias-ply fitment, radial-equivalent choices include 165R15, P165/75R15, and P175/70R15, each of which should be matched to the wheel and vehicle setup.
Look closely at wheel width, overall tire dimensions, and clearance around the suspension, steering, and body openings before making the switch. It also helps to inspect the condition of the wheels themselves, since an older car may still have parts that are serviceable for one tire type but not automatically ideal for another.
Choosing the Right Tire
What should I consider when choosing a 165R15 tire for a 1968 Fiat 1800?
A 165R15 tire is relevant to the 1968 Fiat 1800 B Sedan, so the first consideration is confirming that the car is the Sedan and still uses 15-inch wheels. From there, the main choices are radial series, sidewall treatment, and wheel-width compatibility, since 165R15 appears in several different product families.
Some 165R15 options are blackwall, while others use narrow or wide whitewalls for a more restoration-oriented appearance. Rim-width ranges also vary slightly by product, so comparing those details can be just as important as choosing between Michelin, Vredestein, BFGoodrich, Firestone, American Classic, or Coker Classic.
What sidewall styles are available for 1968 Fiat 1800 tires?
Sidewall choices for the 1968 Fiat 1800 include blackwall, narrow whitewall, and wide whitewall, depending on the size selected. The broadest sidewall variety appears in 165R15 for the B Sedan, while 590-15 also offers both blackwall and wide whitewall choices. The 175R14 Wagon radials shown here are blackwall.
That means appearance can be matched to the character of the car without changing the actual fitment category. A blackwall usually gives a simpler European look, while narrow and wide whitewalls create a more stylized period presentation, so the right choice often depends on whether the Fiat is being preserved, restored, or driven casually.
What brands offer tires for the 1968 Fiat 1800?
Tires for the 1968 Fiat 1800 are available from Michelin, Vredestein, BFGoodrich, Firestone, American Classic, Coker Classic, and Avon. Brand availability depends on the exact size, with the largest spread appearing in 165R15, while 590-15 and 175R14 have narrower but still distinct selections.
The useful comparison is not brand name alone but how each option lines up with your size, construction, sidewall style, and wheel setup. A Sedan owner shopping 165R15 has a wider range of radial series and whitewall choices, while buyers in the bias-ply or 14-inch Wagon sizes will naturally be comparing a smaller group.
Restoration & Appearance
Which tire should I choose for a period-style 1968 Fiat 1800?
A period-style 1968 Fiat 1800 usually starts with the correct primary size for the sub-model and the construction that matches the look you want. For the B Sedan, that can mean 590-15 in bias-ply form or 165R15 in a classic-style radial. For the Wagon, the comparable choice is between 6.40-14 bias-ply and 175R14 radial.
Bias-ply sizing generally gives the most traditional presentation, while a radial can still look appropriate if the sidewall style and overall character suit the car. Buyers pursuing exact originality should compare any tire decision against marque-specific references or restoration records instead of assuming every correct-size tire matches factory delivery.
Which sidewall style suits a period-style 1968 Fiat 1800?
A period-style 1968 Fiat 1800 can be presented with blackwall, narrow whitewall, or wide whitewall tires, depending on the size and product chosen. The Sedan's 165R15 size offers the greatest sidewall variety, while 590-15 also appears in blackwall and wide whitewall forms. The Wagon's listed 175R14 radials are blackwall.
Choosing among them is largely an appearance decision once the correct size and wheel diameter are established. Blackwall keeps the look restrained and European, while narrow or wide whitewalls create a more decorative vintage impression, so the right answer depends on whether the car is being preserved as a subtle driver or styled more prominently.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1968 Fiat 1800?
Yes, modifications can affect tire fitment on a 1968 Fiat 1800. Aftermarket wheels, wheel-width changes, suspension alterations, or bodywork changes can all alter how a 14-inch or 15-inch tire sits in the car. That is especially important here because the model already has sub-model-specific wheel diameters and both bias-ply and radial fitment paths.
A car that has been lowered, widened, or fitted with replacement wheels should be measured rather than judged by year and model alone. Checking wheel diameter, wheel width, steering clearance, and fender clearance before mounting tires helps prevent choosing a size that matches the catalog fitment but not the car's present configuration.
What should I inspect before driving a 1968 Fiat 1800 on new tires?
Before driving a 1968 Fiat 1800 on new tires, inspect the wheels for condition and confirm that the tire size matches the actual rim diameter on the car. It is also smart to look over valve stems, wheel hardware, and the surrounding suspension and steering components so the new tires are not being installed onto a neglected setup.
After installation, check inflation, make sure the tires clear the body and suspension through the steering range, and watch for any signs of rubbing or air loss during the first miles. On a collector car that sits often, an early recheck helps catch issues before they become more serious road-use problems.
How should 1968 Fiat 1800 tires be maintained on a collector car?
Collector-car tire maintenance for a 1968 Fiat 1800 starts with regular pressure checks and visual inspections, even if the car is driven only occasionally. Tread depth alone is not enough on an older-use vehicle, because sidewall cracking, bulges, cuts, flat spotting, and slow air loss can appear long before the tires look worn out.
Storage conditions matter as much as mileage, so keeping the car away from prolonged sunlight, heat, moisture, and ozone sources helps preserve the tires. Frequent short inspections are worthwhile before local drives, and a more careful once-over before any longer trip can reveal age-related issues that a parked collector car may hide.
