900-20 Tire Size Guide

The 900-20 is a numeric tire size in which 900 identifies the nominal section width in inches and 20 identifies the rim diameter in inches. In practical terms, this size points to a tire that is about 9.0 inches wide and built for a 20-inch wheel.

Unlike a modern P-metric size, the 900-20 code does not directly spell out an aspect ratio, speed rating, or load index in the size itself. It is an older bias-ply format commonly tied to antique and early postwar applications, so buyers usually need to confirm the exact tire's construction details, load rating, and wheel requirements from the tire itself rather than expecting every specification to be embedded in the code.

The 900-20 tire fits a 20.0-inch wheel, which is 508.0 millimeters at the bead seat. That rim diameter must match exactly, because tire diameter and wheel diameter are separate measurements and the bead will only seat on the correct rim size.

Wheel width matters as well as wheel diameter. In this size, published fitments span 6.50 to 9.00 inches wide, so the exact tire construction and duty level should be matched to the wheel you plan to use. A narrower wheel changes sidewall shape and can increase crown, while a wider wheel flattens the profile and may alter clearance, steering feel, and how period-correct the tire looks on an antique vehicle.

The 900-20 tire has a section width of 9.0 inches, which is about 228.6 millimeters. Section width is measured at the widest point of the inflated sidewalls rather than across the tread face.

Clearance checks should be based on section width because the sidewall bulge is often what comes closest to fenders, leaf springs, steering arms, and brake hardware. Tread contact width is usually narrower, so using tread width as your only guide can be misleading. On an antique car or light truck, that extra sidewall width can also influence the visual stance, especially when the vehicle has tight front-fender clearance or full-lock steering movement.

Yes, 900-20 and 9.00-20 are common written variants of the same basic size. The decimal point is simply another way of presenting the same nominal width, and buyers will also see formats such as 90020, 900 20, 900X20, and 9.00X20.

Notation differences do not eliminate the need to verify the exact tire itself. Older sizing systems often use multiple written forms, but the tire's actual casing type, rim-width range, and load rating still have to match the vehicle and wheel. When comparing listings or old service documents, treat these aliases as alternate spellings first, then confirm that the wheel diameter, intended application, and construction style align with the setup on the vehicle.

The 900-20 is commonly a tube-type fitment and is often set up with a tube. Even so, tube use is a wheel-and-tire-system question rather than a size question, so the final decision should be confirmed against the exact tire and wheel being used.

Antique and military-style wheel designs vary widely, and rim construction can matter just as much as tire size. Split-ring, lock-ring, and older service wheels may have different requirements than later one-piece rims. Before assembly, inspect the wheel carefully, confirm whether the rim is intended for tube use, and match the tube, flap, and tire to the actual application so the finished assembly is appropriate for the vehicle and how it will be driven.

The 900-20 tire weighs between 63 and 113 pounds in the current Military & Truck offerings. That spread reflects major differences in casing design and duty level even though the stated size remains the same.

Weight matters because a much heavier tire changes unsprung mass and can influence steering effort, ride response, and how the suspension reacts over rough roads. On an antique truck or utility vehicle, that may be acceptable or even expected, but it should still be considered before mixing tire types. Compare tire weight along with load rating, rim-width range, and intended service so the finished set behaves consistently from corner to corner.

The 900-20 is most closely associated with prewar to early postwar passenger cars, light trucks, and military-style utility vehicles that used tall 20-inch wheel packages. It belongs to an older numeric bias-ply sizing system, so it is usually relevant to antique equipment rather than later mainstream passenger-car applications.

Original fitment still needs to be verified vehicle by vehicle. Many antique platforms changed wheel design, brake hardware, and body clearance during production, and military or commercial service often introduced later substitutions. Check original documentation, inspect the wheel itself, and compare overall tire bulk to the available space at the fender, steering linkage, and suspension before treating the 900-20 as the right match for a particular vehicle.

The 900-20 is used on wheel widths from 6.50 to 9.00 inches, depending on the exact casing and duty level. That range is broader than many buyers expect, which is why the tire's intended use matters as much as the size code.

A 6.50-inch wheel and a 9.00-inch wheel do not give the tire the same profile. Narrower wheels pull the sidewalls inward and create a taller, rounder shape, while wider wheels spread the casing and can change footprint shape and clearance. On an antique restoration, that also affects appearance. Buyers should match the chosen tire to the actual wheel width and use pattern instead of assuming every 900-20 behaves the same on every 20-inch rim.

The 900-20 is often a strong restoration choice when an antique vehicle originally used a tall numeric bias-ply fitment on a 20-inch wheel. Bias-ply construction usually preserves the visual profile, sidewall character, and road feel expected from prewar to early postwar machinery more faithfully than a later-style substitute.

Authentic appearance is only one part of the decision. The exact vehicle, wheel type, and intended road use still determine whether this size makes sense, especially when later service replacements have altered the setup over time. If originality matters, compare the tire's overall proportions and wheel-width needs to factory documentation and surviving examples, then confirm that the load rating and clearance also support how the vehicle will actually be used.

The 900-20 uses bias-ply construction, so its road manners tend to reflect the flexible, tall-sidewall character expected from older truck and antique vehicle tires. Steering response, tracking, and ride feel are usually different from modern radial behavior, with more influence from casing shape and vehicle setup.

Driving experience depends heavily on the condition of the suspension, steering linkage, alignment, wheel condition, and the tire's duty level. A properly sorted antique vehicle can feel stable and correct within its original design limits, but buyers should not expect a bias-ply 20-inch fitment to mimic a modern passenger radial. For that reason, it makes sense to evaluate the full chassis and intended speed range along with the tire size itself.

Yes, different 900-20 casings can change the driving experience noticeably. In this size, current offerings vary substantially in weight and load capability, which means they can differ in stiffness, steering effort, and how the vehicle reacts to bumps or rough surfaces.

Heavier-duty versions may suit utility or military-style service better, while lighter versions can feel more compliant on vehicles that do not need maximum carrying capacity. The key point is that the size alone does not define the road feel. Compare casing weight, wheel-width requirement, and paired load-and-pressure rating before mixing tires across an axle or building a full set, because consistency matters as much as nominal size when you want predictable behavior.

The 900-20 can be used on today's roads when the tire, wheel, and vehicle are all in proper condition, but it should be approached as an antique bias-ply fitment rather than a modern all-purpose replacement. Road behavior, braking feel, and tracking are influenced by the older construction style and the vehicle's original design.

Modern use calls for realistic expectations. Inspect the tire carefully, confirm the load requirement, and make sure the wheel assembly is correct before any extended driving. Interstate travel, braking distances, and lane-tracking confidence all depend on factors beyond size alone, including tire age, inflation, suspension wear, alignment, and steering condition. A careful setup can be serviceable, but this remains an old-format tire size that rewards conservative, well-maintained use.

STA offers the 900-20 in the current selection. Even within one brand, this size spans more than one casing and load specification, so the exact tire should be chosen for the vehicle's intended duty rather than by size name alone.

Brand choice is only part of the quality decision on an antique size like this. Buyers should also compare construction consistency, wheel-width compatibility, load rating, and whether the tire's overall character suits a restoration, military-style display vehicle, or working truck. Keeping the same brand and specification across the full set is usually the cleaner approach when you want balanced appearance, predictable handling, and matched service requirements.

A quality 900-20 tire should match the vehicle's real load needs, mount correctly on the intended wheel width, and reflect the bias-ply character expected from this antique size. On a practical level, the important checks are casing type, load-and-pressure pairing, tire weight, and how well the tire suits the wheel and use pattern.

Period appearance matters, but it should be balanced with consistency and fitment discipline. Compare the tire's proportions to the vehicle's original look, then make sure the wheel diameter, width, and tube arrangement are correct for the assembly. For a truck or military-style build, using a tire that is unnecessarily heavy or overbuilt can change steering and ride just as surely as using one that is under-specified for the load.

Using a matched set of 900-20 tires is the safest and most predictable approach for most antique vehicles. Even when the size code is identical, differences in casing weight, load rating, and profile on the wheel can change how the vehicle steers, rides, and carries weight.

Mixed specifications are especially noticeable on older chassis with manual steering and less forgiving suspension geometry. Matching the full set helps preserve even stance, balanced response, and a uniform period appearance. If a complete set is not possible, the replacement tire should at least match the others in construction type, service character, and wheel-width requirement so one corner of the vehicle does not behave differently from the rest.

The 900-20 should be stored like any collector-vehicle tire: clean, dry, and away from direct sunlight, high heat, electric motors, and ozone sources. Bias-ply tires on vehicles that sit for long periods also benefit from periodic movement so one spot is not left carrying the vehicle's weight month after month.

Seasonal storage matters because age-related deterioration can develop even when tread looks barely used. Owners should inspect for cracking, weather checking, cuts, sidewall bulges, and air loss before returning the vehicle to service. If the vehicle remains parked for extended stretches, reducing exposure to moisture and keeping the tires off contaminated concrete can also help preserve the casing and maintain a more consistent ride when the vehicle goes back on the road.

The 900-20 should be inspected regularly, especially before longer drives, event use, or carrying heavier loads. Focus on cracking, bulges, cuts, loose or damaged valve hardware, irregular wear, and signs that the tire has been run at the wrong inflation for its actual service.

Bias-ply tires can mask age issues until a close inspection is performed, and antique vehicles often spend enough time parked that deterioration is easy to overlook. Inspection should include the wheel as well as the tire, particularly on older truck or military-style assemblies. When wear patterns look uneven, it is wise to check alignment, wheel condition, and suspension play rather than assuming the tire size itself is the cause.

The 900-20 is commonly a tube-type fitment, but tube use still has to be confirmed as part of the complete wheel-and-tire assembly. The exact rim design, tire construction, and service hardware all affect whether a tube, flap, or related components are required.

Older 20-inch wheels deserve extra scrutiny because serviceable parts, rim condition, and prior modifications can vary from one vehicle to another. Before mounting, inspect the wheel carefully and confirm the tire maker's guidance for the exact casing being used. A correct tube setup is not just about size; it depends on the actual wheel design, the tire's intended application, and the condition of every sealing and support component in the assembly.

The 900-20 should be replaced when age, cracking, cuts, bulges, persistent air loss, impact damage, or casing deterioration raise doubts about its condition, even if the tread depth still looks usable. Antique tires can age out long before they wear out, particularly on vehicles that see limited annual mileage.

Time, storage conditions, sunlight, heat, and ozone exposure all influence roadworthiness. Before any extended trip, inspect the sidewalls and tread closely and consider how long the tires have been in service, not just how much rubber remains. On an older truck or military-style vehicle, cautious replacement timing is especially important because the tire is carrying a tall, heavy assembly that may be asked to support substantial load.

The 900-20 spans multiple load ratings in current Military & Truck offerings, from 4,000 pounds at 65 psi to 7,000 pounds at 90 psi. Buyers should match the exact tire's rating to the vehicle's actual operating weight and intended use rather than assuming every 900-20 carries the same load.

Load capacity only applies at the inflation pressure paired with that rating, so the numbers must be read together. A restoration, parade vehicle, utility truck, and military-style hauler may all use the same nominal size while demanding different service margins. Confirm the axle loads, wheel suitability, and tire markings before installation so the selected casing supports the real-world duty cycle instead of only matching the old size code.

The most important checks for the 900-20 are tire condition, correct wheel diameter, wheel width compatibility, proper assembly for tube-type use when required, and a load rating that matches the vehicle's needs. Buyers should also inspect the wheel itself, because older 20-inch assemblies can be as critical to safety as the tire.

Before road use, confirm there is no interference at steering lock or suspension travel and look for any signs of cracking, impact damage, or prior wheel repairs. Local road-use requirements and inspection expectations can vary, so current sidewall markings and overall assembly condition deserve review as well. When there is any uncertainty about wheel design, tube hardware, or serviceability, a qualified tire professional should inspect the combination before the vehicle returns to regular use.