Q&A about tread scrubbing on trailer tires

Q&A about tread scrubbing on trailer tires

 

Question from a reader:
“I have a question regarding interply shear or scrubbing common on double or triple axle fifth wheels. I have a double axle and try to avoid sharp turns and U-turns as much as possible, but I see visible signs of scrubbing on the tread of my tires. It looks like flat spots on the edge of the tires. After a turn, I can go back and see the rubber I’ve scrubbed and left on the road. It’s frustrating. I have the axles aligned and tires balanced once a year and have individual wheels weighed occasionally. I try to keep side-to-side and front-to-back weights within a couple hundred pounds. I currently carry 85%-90% of load capacity, or about 3300-3400 lbs. per tire.

“My question is: Would going to the next load range up (from G to H) or going to a harder compound tire reduce this problem? I currently use Goodyear G614RST tires, size LT235/85R16. I’ve heard in the past that Michelin uses a harder compound in their tires, which makes for a little stiffer ride, but might this overcome some of the effects of scrubbing? I feel I could get a lot more miles out of my RV tires if I could reduce the flat spots or sculpting caused by unavoidable scrubbing.”

My answer:
Axle alignment or wheel balance isn’t the problem. The center of tire rotation is not pointed to the center of the turn radius so the tires are always being dragged around every turn. It is just worse on tight turns.

Lowering the percentage of max load capacity is a good idea. Don’t forget that it is the air pressure that determines the load capacity not the Load Range (G to H). You will gain nothing from a load range change if you do not also increase the air pressure. You do need to confirm the wheel max psi capacity which, for some wheels, is not easy to do as some wheel manufacturers do not have high pressure ratings easily available.

Regarding tread compound: Sometimes it isn’t just the hardness of the rubber but also the tread pattern that can affect scrubbing wear.

In general, the tread scrub is a function of dragging a trailer around.

Send your questions to me, Roger, at Tireman9 (at) gmail.com

##RVT783

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4 thoughts on “Q&A about tread scrubbing on trailer tires

  1. Cam

    What is scrubbing?

    1. Roger Marble

      Scrubbing would be the term for a tire sliding partially sideways rather than rolling. Tires in trailer application are being dragged around turns. The center of rotation of the wheel & tire does not point to the center of the radius. There is a sketch in this blog post
      http://www.rvtiresafety.net/2016/05/question-on-interply-shear-on-trailer.html

      that shows the center of rotation for the tires on the tow vehicle point to the center of the turn while the center for the trailer tires do not go to the center of the turn.

  2. Barry

    If you have the opportunity, a little cat litter will reduce the scrubbing. I have also just used a water hose to wet the surface prior to backing my fiver into my parking space to reduce scrubbiing.

    1. Roger Marble

      Barry, you are correct. Wet clay or ice in the winter would allow the tires to slide across the surface easier with less wear of the tire tread rubber. Sand and loose gravel or dirt would also decrease the tread wear vs concrete or asphalt.

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