In addition to maintaining proper tire pressure, these items should be on everyone’s RV tire-safety checklist.
✔ TREAD WEAR LIMITS
Tire guides published by Goodyear and Michelin agree that tires should be replaced when the tread is worn down to 2/32-inch. The most accurate way to measure is with a tread depth gauge, available at Napa and other auto parts stores. Goodyear also notes that federal regulations require replacement of front tires on vehicles with front gross axle weight ratings of more than 10,000 pounds when tread is worn to 4/32-inch.
Beyond the underinflation/overloading issue, improper leveling may be the second greatest sin. Tires should be supported uniformly while the coach is parked. If you’re using blocks or boards to level the motorhome, always support both dual tires, not just the outside tires. If any of the tread is unsupported, it can cause internal damage that might not be obvious at the time.
Damage is always a possibility, and tires should be closely inspected at frequent intervals for bulges, cuts, nails or screws lodged in the tread, anything lodged between dual tires and other irregularities. Tire damage may not show up immediately after an incident, such as running over a large piece of debris. Damage to the tire carcass may show up later. All tires should be checked, especially inside duals.
✔ WEATHERING, CRACKING, CRAZING
Weathering, cracking and crazing tend to appear in tire sidewalls after several years, and they may become a concern. They can be a spider web of small cracks, or a line of more significant cracks around the circumference of the tire. How much is too much? Michelin as well as Goodyear recommend replacement if the cracks are more than 2/32-inch deep, especially if tire cord is showing.
If front wheel alignment is out of spec, accelerated tire wear will ensue, and it’s best to catch that early. Measure tread depth across the tire to determine uneven wear patterns. Balance wheels when new, and as needed afterward if vibration occurs — or any time a tire has been dismounted.
✔ TIRE AGE
Age may be an issue with motorhome tires even if they are not worn out or cracked. Michelin states that service-related issues such as tread wear may prompt replacement as tires age, but that they should be replaced regardless of such issues if they’re older than 10 years. Goodyear chooses not to state a specific replacement date, recommending instead to base replacement on service issues and to arrange for a Goodyear dealer inspection when appropriate. In lieu of specific recommendations of individual tire manufacturers, the generally accepted time-out factor for tires is seven years. How to determine age? Check the DOT number on the tire sidewall; the last three or four numbers in the series will be the week and year of production, i.e., 1011 translates to the 10th month of 2011. Although it’s unusual, a new motorhome may be fitted with tires that are a year or more old, so age of the coach cannot be relied upon to indicate tire age.
Tires contain protectants that gradually work their way to surface while they’re rolling; harsh cleansers should not be used. A mild soap/water wash is suitable. Protectants that contain petroleum distillates can be harmful.
Steel valve stem caps should be used. Rotate tires if uneven wear is detected (check tire manufacturer’s RV tire guide for rotation diagram).