Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

CalandLinda · 09-05-2020, 08:50 PM

A posting recap, than I’m out of this one for good.

First is a referral back to post #7.

Misapplication; it’s a very misunderstood word with RV trailer tire applications. When reading tire warranties you’ll always find that misapplications apply to all replacement tire fitments. The basic description of a tire misapplication for RV trailers is; replacement tires must be the same designated size as the Original Equipment tires or on approval/optional recommendation by the vehicle manufacturer (An approval/recommendation only applies to the year and model number mentioned in the paperwork. You’ll also find a similar statement in your trailer’s owner’s manual under the reference “tire size”. It’s not a misapplication to add a load capacity to replacement tires of the same designated size, such as using a ST225/75R15 LRE to replace a ST225/75R LRD. Wheel PSI for the LRE must be met.

The RVIA 10% load capacity recommendation is just that, a recommendation. It has nothing to do with government regulations or standards which are unchanged. It’s just something the RV trailer manufacturers must do to stay in good standing with the large RVIA organization.

Wheels that provide a load capacity and PSI rating of a replacement tire with more load capacity than the OE tires don’t have to be changed. Wheels are only required to carry the load of the vehicle certified GAWRs. Not overloading the GAWRs is an owner’s responsibility.

When modifications for lifting your trailer are performed, it’d be a good idea not to exceed the maximum height allowed in the state of registration.

Remember: The information on the vehicle certification label, once transferred to a consumer, can only be changed by the vehicle manufacturer or a certified vehicle modifier.

I feel compelled to insert this one statement from FMVSS 571.120 paragraph S5.3.1 Tires. The size designation and the recommended cold inflation pressure for those tires such that the sum of the load ratings of the tires on each axle is appropriate for the GAWR. That's the bottom line, minimum requirement and is found on the vehicle certification label.

Just in case you don’t want to look it up, here is a verbatim quote from the Keystone generic owner’s manual (page #21).

Tire Size:

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire dealer.”

My reference materials: FMVSS (standards) – USTMA standards manual for RVs – Keystone owner’s manual.

09-05-2020, 08:50 PM	#54
CalandLinda Montana Master Join Date: Jan 2015 Location: Taylors Posts: 562 M.O.C. #15948	A posting recap, than I’m out of this one for good. First is a referral back to post #7. Misapplication; it’s a very misunderstood word with RV trailer tire applications. When reading tire warranties you’ll always find that misapplications apply to all replacement tire fitments. The basic description of a tire misapplication for RV trailers is; replacement tires must be the same designated size as the Original Equipment tires or on approval/optional recommendation by the vehicle manufacturer (An approval/recommendation only applies to the year and model number mentioned in the paperwork. You’ll also find a similar statement in your trailer’s owner’s manual under the reference “tire size”. It’s not a misapplication to add a load capacity to replacement tires of the same designated size, such as using a ST225/75R15 LRE to replace a ST225/75R LRD. Wheel PSI for the LRE must be met. The RVIA 10% load capacity recommendation is just that, a recommendation. It has nothing to do with government regulations or standards which are unchanged. It’s just something the RV trailer manufacturers must do to stay in good standing with the large RVIA organization. Wheels that provide a load capacity and PSI rating of a replacement tire with more load capacity than the OE tires don’t have to be changed. Wheels are only required to carry the load of the vehicle certified GAWRs. Not overloading the GAWRs is an owner’s responsibility. When modifications for lifting your trailer are performed, it’d be a good idea not to exceed the maximum height allowed in the state of registration. Remember: The information on the vehicle certification label, once transferred to a consumer, can only be changed by the vehicle manufacturer or a certified vehicle modifier. I feel compelled to insert this one statement from FMVSS 571.120 paragraph S5.3.1 Tires. The size designation and the recommended cold inflation pressure for those tires such that the sum of the load ratings of the tires on each axle is appropriate for the GAWR. That's the bottom line, minimum requirement and is found on the vehicle certification label. Just in case you don’t want to look it up, here is a verbatim quote from the Keystone generic owner’s manual (page #21). Tire Size: “To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire dealer.” My reference materials: FMVSS (standards) – USTMA standards manual for RVs – Keystone owner’s manual.