To read tire size, load index, and speed rating for Ford Transit 350 XLT, start with the tire and loading label on the driver’s door area and the owner’s manual for the exact model year. Transit 350 XLT describes a family of vans, not one tire setup: passenger and cargo bodies, wheel options, axle configurations, and model years can differ. The markings on the sidewall help identify a tire, but they do not override the vehicle’s approved size, load, pressure, or fitment requirements.
Read a tire size string from left to right
A tire marking might look like P235/65R16 103T or LT245/75R16 E. The first portion identifies tire type and nominal width, aspect ratio, construction, and wheel diameter. The service description after the size can include a load index and speed symbol. Light-truck tires may show a load range letter or a two-number load index for single and dual use. Markings vary, so consult the tire maker’s guide for the exact format on the tire you are reading.
The “R” in a common size means radial construction; it is not the speed rating. The final letter in the service description is usually the speed symbol, while the number before it is the load index on many passenger-type tires. For LT tires, load capacity depends on load range and inflation pressure as well as the marking. Do not infer a safe vehicle load from one symbol or from the tire’s maximum sidewall pressure.
Understand load index and load range
A load index is a code associated with a maximum carrying capacity under specified test conditions. It is not a weight in pounds and should be looked up in a current tire reference. Some light-truck tires list two load-index numbers, which can represent different service conditions such as single or dual tire use. The correct application and pressure matter. Replacement tires should meet the vehicle manufacturer’s stated load capability for the axle and configuration.
Load range is a letter designation used on many LT tires and is related to construction and load/inflation capability. It is not the same as load index, and it does not mean that choosing a higher letter automatically improves handling or allows overloading the van. The tire must be compatible with the wheel, vehicle, and specified pressure. A heavier-duty tire may ride differently and can have different pressure requirements; confirm the complete application with Ford or the tire maker.
Read the speed symbol in context
The speed symbol indicates a tire’s tested speed capability under defined conditions, not the safe speed for every load or road. Speed capability can be affected by pressure, load, condition, and use. Choose a replacement speed rating that meets the vehicle’s requirement and follow current manufacturer guidance. Never use a rating as permission to exceed posted limits, vehicle ratings, or safe operating conditions.
Apply the markings to a Transit 350 XLT
Before shopping, photograph the door label and read the size and recommended cold pressures. Record the model year, passenger or cargo body, wheel size, axle and wheel configuration, and any dual rear wheel equipment. Compare the tire size, load index or range, speed symbol, and service description with Ford’s manual and the tire maker’s application catalog. NHTSA advises using the tire size specified on the vehicle’s placard or another manufacturer-recommended size; its TireWise guide also explains pressure and basic tire safety.
The pressure printed on the tire sidewall is generally a maximum for that tire, not the Transit’s everyday target. Inflate cold tires to the vehicle label’s value for the specified configuration. If the van is converted, modified, or fitted with a nonstandard wheel and tire combination, consult Ford, the conversion builder, and a qualified tire professional. A change may affect load capacity, clearance, handling, speedometer accuracy, and TPMS operation.
For related Transit tire topics, see our Ford Transit 250 load-range guide, winter fitment guide for Transit 350 XLT, Transit 250 tire inspection guide, and Transit 350 XLT tire overview. These pages cover related questions, but their size and body-style details do not establish fitment for your van.
For comparable light-commercial tire topics, read our guides to load range for a Ford E-250, E-250 tire pressure under load, and F-250 tire load range. Those models have different specifications; use the Transit placard and correct owner manual for Transit fitment.
Read the complete service description
Do not stop after decoding width and wheel diameter. A tire’s full service description may include a load index and speed symbol, while a light-truck tire can also display load range and single/dual load details. Record all of the sidewall markings and compare them with the door label and the current tire maker’s catalog. The same nominal size can be built in different constructions or load versions, and two tires with similar-looking lettering may not have the same capacity at the same pressure. Check whether the tire is intended for passenger, light-truck, or commercial-van service. If an online listing omits load index, speed rating, or type, contact the seller or manufacturer before purchase. Keep a photo of the sidewall and label with the service record so a future replacement can be checked against the exact specification. For a converted or modified van, confirm the finished vehicle’s axle loads and wheel limits with the converter and a tire professional.
Frequently Asked Questions
Where can I find the correct tire size for my Ford Transit 350 XLT?
Check the tire and loading label on the driver’s door area and the owner’s manual for your exact model year and configuration.
Is load index the same as load range?
No. Load index is a numeric code tied to capacity; load range is a tire designation related to construction and load/inflation capability.
Can I use a tire with a higher load range?
Only if it is approved for the vehicle, wheel, and intended application. Confirm size, fitment, pressure, and handling considerations with the manufacturers.
Does the sidewall maximum pressure tell me how much air to use?
Use the Transit’s placard and manual for cold inflation pressure. The sidewall value is not a substitute for the vehicle’s specified pressure.
Can a speed rating be lower than the original tire’s?
Do not reduce the required rating without confirmation from Ford or a tire professional. Match or exceed vehicle requirements and obey safe speed limits.
Final Words
Read Ford Transit 350 XLT tire size, load index, load range, and speed rating from the sidewall, then verify each item against the correct door label, owner’s manual, wheel, and tire-maker catalog. Use the vehicle placard for cold pressure and confirm any conversion or alternate size with qualified sources. These markings describe important capabilities, but none permits exceeding the van’s ratings or operating limits.
