RV Tire Safety: How to avoid tire “flat spotting” when parked

with RV tire expert Roger Marble

Here’s a recent post from an RV forum:

“I’m no tire engineer but I always thought of a ‘flat spot’ as an area ground off from a long skid. The old bias ply tires of years ago would ‘deform’ or become ‘out of round’ (especially in cold weather), but a few miles of rotation would flex it back into shape. But that’s all just semantics.”

Well, I am a Tire Engineer, and the correct terms are “flat spot” for an out-of-round condition and “brake flat spot” for having an area of the tread worn off due to locking up the brakes so the tire is dragged along the road and does not rotate. When I was racing I would sometimes lock up the brakes to avoid a spinning car. This would give a strong vibration and we would have to change the tire at the next pit stop.

You can develop “flat spot” from long-term parking. The degree or level or amount of this type of flat spotting depends on time, temperature load, inflation pressure, rubber chemistry and tire construction.

You can decrease this flat spotting with: Lower load or higher inflation, or not parking when the tire is still hot, or keeping the tire out of direct sunlight. The owner has no control over the rubber chemistry or tire construction.

FYI: In general, tires with nylon cap ply (seen in tires with higher speed rating) tend to develop and hold the flat spot longer, but I would not reject tire purchase because of the nylon cap ply as that might give you more life of the tire.

You can see and probably measure the amount of flat spotting from either brake lock or long-term parking if you check with a “free spin” inspection as seen in the video in THIS blog post.

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

 ##RVT951