tire pressure
just had new G rated Sailun tires put on rig. These tires are rated at 110 psi Our rig weights around 19,000 lbs Am I okay to keep the psi at 90lbs or should I always keep them at 110 psi?
Forum Discussion
Tire inflation pressures are not supposed to be as complicated as they are often presented in this form of discussion.
Most of the misunderstandings comes from complicating the subject with unneeded information.
For more than 99% of the vehicles in this thread, the governing body is the DOT via NHTSA and their FMVSS. The industry standards are from the automotive & tire industries.
Recommended, a key word in tire inflation pressures. It’s the best fit. You inflate your tires in the morning to a recommended cold inflation pressure you’ve been told to use. Then you get underway. After a mile or two the pressure has climbed to a higher value, as it’s supposed to do. You cannot correctly set it again until the tire cools.
So, where did the original recommendation originate? The governing body, with it’s wisdom, determined that the vehicle manufacturer is the most qualified for that task and has given them the sole responsibility for setting cold recommended tire inflation pressures for all Original Equipment (OE) tires. Once certified to a particular vehicle, the recommendation is passed on to all replacement tires and supported by an industry standard that simply says that replacement tires must provide an inflation pressure equal to, or greater than what the OE tires provided with the vehicle manufacturer recommended cold inflation pressure found on the vehicle certification label.
Now some problem areas. Special circumstances and options. Foreseen special circumstances are normally identified by the vehicle manufacturer and will be outlined in the vehicle owner manual. Optional conditions are often whims for load variations or even a more comfortable ride condition. Circumstantial & optional conditions have one thing in common, they should never be below the vehicle manufacturers certified recommendations or higher than the inflation pressure needed for maximum tire load capacity. Reference for that can be found in the USTMA publications or in just about any major tire manufacturer’s Standards of Operations Procedures (SOP) manuals and/or tire data books.
Another problem, commercial tires. They, when used on commercial vehicles are inflated differently. The commercial regulations (FMVSA) inflate to the load carried. They do not have a provision for a normal “recommended cold inflation pressure”. Many of those tires are used on large RV trailers and Motor Homes. When those vehicles are built and certified to FMVSS standards the commercial regulations are not applicable. In the case of RV trailer tire fitments, any design used becomes a trailer tire. The vehicle certification label displays the tire’s designated size. It is the standard for that trailer. The vehicle manufacturer can (maybe, or not often) recommend options.
Just about any mechanical thing we use has limits. In this context, those limits are normally well documented. Beyond those limits is the gray or unknown factors. When we enter into those areas, we can go too far, because we don‘t know how far to go, unsatisfactory things may - probably will - happen.
Bottom line; For RV trailer tires, always use the trailer manufacturer’s recommended cold inflation pressures. Make sure all replacement tires have a load capacity via inflation pressure that equals or exceeds the load capacity the OE tires provided at the vehicle manufacturers recommended cold inflation pressures. USE steel valve stems.
Most of the misunderstandings comes from complicating the subject with unneeded information.
For more than 99% of the vehicles in this thread, the governing body is the DOT via NHTSA and their FMVSS. The industry standards are from the automotive & tire industries.
Recommended, a key word in tire inflation pressures. It’s the best fit. You inflate your tires in the morning to a recommended cold inflation pressure you’ve been told to use. Then you get underway. After a mile or two the pressure has climbed to a higher value, as it’s supposed to do. You cannot correctly set it again until the tire cools.
So, where did the original recommendation originate? The governing body, with it’s wisdom, determined that the vehicle manufacturer is the most qualified for that task and has given them the sole responsibility for setting cold recommended tire inflation pressures for all Original Equipment (OE) tires. Once certified to a particular vehicle, the recommendation is passed on to all replacement tires and supported by an industry standard that simply says that replacement tires must provide an inflation pressure equal to, or greater than what the OE tires provided with the vehicle manufacturer recommended cold inflation pressure found on the vehicle certification label.
Now some problem areas. Special circumstances and options. Foreseen special circumstances are normally identified by the vehicle manufacturer and will be outlined in the vehicle owner manual. Optional conditions are often whims for load variations or even a more comfortable ride condition. Circumstantial & optional conditions have one thing in common, they should never be below the vehicle manufacturers certified recommendations or higher than the inflation pressure needed for maximum tire load capacity. Reference for that can be found in the USTMA publications or in just about any major tire manufacturer’s Standards of Operations Procedures (SOP) manuals and/or tire data books.
Another problem, commercial tires. They, when used on commercial vehicles are inflated differently. The commercial regulations (FMVSA) inflate to the load carried. They do not have a provision for a normal “recommended cold inflation pressure”. Many of those tires are used on large RV trailers and Motor Homes. When those vehicles are built and certified to FMVSS standards the commercial regulations are not applicable. In the case of RV trailer tire fitments, any design used becomes a trailer tire. The vehicle certification label displays the tire’s designated size. It is the standard for that trailer. The vehicle manufacturer can (maybe, or not often) recommend options.
Just about any mechanical thing we use has limits. In this context, those limits are normally well documented. Beyond those limits is the gray or unknown factors. When we enter into those areas, we can go too far, because we don‘t know how far to go, unsatisfactory things may - probably will - happen.
Bottom line; For RV trailer tires, always use the trailer manufacturer’s recommended cold inflation pressures. Make sure all replacement tires have a load capacity via inflation pressure that equals or exceeds the load capacity the OE tires provided at the vehicle manufacturers recommended cold inflation pressures. USE steel valve stems.
