Size Isn't All That Matters - Tire Review Magazine

Size Isn’t All That Matters

e and the increased inflation pressure required to support that load.

Similar differences can be found on some applications of sizes 11R22.5 Load Range H and the more popular Load Range G version, and with the Load Range G vs. F versions of a 245/70R19.5. Generally, the wheels used for these tire sizes are designed with enough reserve capacity for the higher loads and inflations of optional heavier duty tires, but this should always be checked if replacing either component.

A somewhat more complex tire situation has developed in the Class 4 through 6 chassis market, and especially with certain types of towable recreational vehicles and commercial trailers.

A number of commercial trailers are typically fitted with 15- or 16-inch wheel diameter tires. The wheelhouse area on these vehicles is often kept as small as possible to maintain a low center of gravity for stability, and to allow the greatest amount of interior space possible given the load carrying capacity.

Most of the smaller units, which may have been fitted with passenger tires in the past, are now equipped with 15- or 16-inch "special ST metric" tires designed specifically for highway service trailers. The tires have a "ST" prefix in front of the size (ST 235/80R16) and have load/inflation ratings different from their same-sized passenger/light truck counterparts.

The growing popularity of larger wheel diameter tires – from 16 to 20 inches ®“ on many performance car models and some pickup trucks further clouds the picture.

Many of the ST tires and some of the LT prefixed light truck tires used in RV and commercial trailer applications require wheels and valve stems that are rated higher than typical passenger/light truck applications.

One example is the LT 235/85R16 Load Range G tire, designed for commercial trailers. This tire can carry as much as 3,750 pounds, but requires a cold inflation pressure of 110 psi, so it must be used only with a special high strength wheel.

Since this same basic tire size is commonly fitted to larger GVW pickup trucks that are popular tow vehicles for the larger trailers, it is quite possible to have the same size tires on both the truck and trailer. But heavier wheels and higher inflation pressures would be mandatory for the trailer; the truck’s tires would have insufficient load capacity for the trailer application.

Back on the RV front, it should be noted that some motor home coaches, usually the larger bus-like units, may call for different tire sizes and/or load ranges for the front vs. rear axles.

Check and Check Again

With all of this complexity and the resulting possibility of misapplication, it’s a good idea to always check several important information sources. Suggestions from several industry professionals include:

®′ Check the vehicle placard – if not available, check the vehicle owner’s manual ®“ to determine the tire size AND load range recommendation of the vehicle maker. If any doubt or question exists, contact the vehicle maker to determine the proper tire size, tire type (prefix) and load range. Tires with a lower load range should never be substituted in an application that calls for a higher specified load range.

®′ Be aware that the tire type prefix (e.g. P, LT, ST) is an integral part of the tire size description. Tires with different prefixes have different load and inflation ratings and should not be substituted for, or mixed with, differently prefixed tires.

®′ Always check the wheel/rim load and inflation ratings to be sure that they are compatible with the tire load and inflation requirements for the application.

®′ Make sure that the valve is rated for the inflation pressure of the tire being used. This is especially important for 15- and 16-inch applications, where snap-in valves can be used for lower inflation pressures and clamp-in valves are required for higher inflations.

®′ Do not assume that the tires on used vehicles are the correct ones for the application. The previous owner may have replaced one or more tires previously.

®′ Do not mix and match radial and bias-ply tires.

®′ Maintain inflation pressures that are recommended by the vehicle maker and are compatible with the ratings on the tire sidewall. If there is any question, contact the OEM or a qualified tire industry professional.

Lest you think that all of this sounds incredibly confusing and impractical to administer, consider that some in the heavy vehicle maintenance industry have been dealing with similar complexity for years. Fire trucks, mobile cranes, and ready-mix concrete trucks are good examples.

But today more and more motor homes and trailers – even some emergency equipment, like ambulances ®“ are being fitted with tires that may be inadequate for the job they are being asked to do, or tires that are specifically designed for that load application.

Keep these customers safe by paying close attention to all these factors.

You May Also Like

EVs, Fleet Management to Aid Commercial Tire Growth

The post-COVID market is bouncing back, which will drive market trends in 2023.


When I was a child, rollercoasters were an awe-inspiring combination of power and adrenaline, a towering marvel of speed and terror to be gazed upon with either great anticipation or great fear– sometimes both. I have always loved knowing how things work, and even at a young age, I appreciated the mechanics of it all: the slow, steady, deliberate creaking of the steep climb, and the unseen forces just out of reach methodically pulling riders toward the unknown.

Last-Mile Delivery Tires Set to Outpace Long-Haul Tire Volumes

Prior to the pandemic, the last-mile delivery (LMD) market was booming. So, when COVID-19 hit, and newly-homebound consumers placed even more online orders — retailers like Amazon shortened delivery times to two days, one day, or even same-day services — and the segment exploded. Related Articles – Goodyear Unveils 90% Sustainable Tire – Goodyear Introduces

Global Tire Manufacturer Ralson Enters US TBR Market

Global tire manufacturer Ralson is entering the U.S. commercial tire market with a new medium/heavy truck tire manufacturing facility and a team of veteran American sales and marketing tire professionals. Ralson debuted its products for the US with its American team at the 2022 SEMA Show in Las Vegas. Related Articles – Maxam Tire Completes

Michelin Releases Agilis HD Z as New Urban and Regional Tire

Michelin North America has released the Michelin Agilis HD Z 19.5 in two sizes to offer fleets with light and medium-duty vehicles durable, long-lasting tires optimized for the stresses of urban and regional environments. The Agilis HD Z 19.5-in. tires will replace the Michelin XZE in two current sizes (225/70R19.5 LRG and 245/70R19.5 LRH) in

Yokohama Tire Launches the 716U UWB Regional Drive Tire

Yokohama Tire’s newest commercial tire – the 716U ultra wide-base – is a weight-savings drive tire that carries more profitability for fleets, the company says. It is available now in the US in size 455/55R225. Related Articles – BKT Highlights Ridemax Radial Floatation Tire for AG, Tank Trucks and Spreaders – CEAT Specialty Tires Increases


Other Posts

Vredestein Launches New Pinza H/T in US

Vredestein Tires has launched its new Pinza H/T line of tires, a highway all-season tire designed for trucks, SUVs and crossovers. According to Vredestein, The Pinza H/T has unique features that keep the comfort of the driver in mind. Related Articles – Goodyear Adds Wrangler HT Tire to Light Truck Lineup – Comparing Trends in

Vredestein Pinza H_T
Goodyear Adds Wrangler HT Tire to Light Truck Lineup

The Goodyear Tire & Rubber Company has added the Goodyear Wrangler Workhorse HT to its Wrangler light truck tire lineup. Goodyear says its Wrangler Workhorse HT provides all-season traction, a confident ride and the strength to go the extra mile. Related Articles – BKT Tires Launches Agrimaxfactor Tire For Tractors – Michelin’s Enviro System Unveils

Comparing Trends in All-Season and All-Weather Tire Segments

When it comes to all-season and all-weather tires, consumer expectations have been a driving force in both segments, affecting everything from OE fitments and sales trends to tire performance. Essentially, consumers want the convenience of not having to swap tires every winter, as well as the safety and performance provided by capable all-weather tires, according

All season all weather vredestein hypertrac
Continental Debuts Enthusiast-Driven ExtremeContact Sport 02

From timed autocross laps to drifting on a skid pad and mastering knee-jerk braking and turns on a raceway, dealers, influencers and members of the media were treated to a crash course in performance racing while testing out Continental’s newest UHP summer tire, the ExtremeContact Sport 02. Related Articles – Mickey Thompson Unveils 42-, 44-in.