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Thursday, August 28, 2014

Strange wear on front of Class-A

Jim said:  "I attended one of your programs at the (FMCA) Redmond rally.  It was most interesting, and it convinced me that you may be the one person who has the background to identify the cause of my issue.  I’ve shown the photos to about 4 different dealers of Goodyear RV tire dealers and I’ve gotten 4 different answers.  I’ve also sketched the phenomena for the service manager at Josam alignment in Orlando, and he says it’s just typical of Goodyear tires, with no way to correct the situation.  It’s also been identified as “rivering,” which has been the subject of numerous posts on RV forums.
My coach is a 2011 34’ Newmar Ventana, on a Freightliner chassis.  I have had the coach weighed and, based on weight plus a safety factory, run them at about 85 PSI cold.  The deeper wear groove at the first groove happens on both the inside and the outside of both front tires, but not on the rear duals.
If you would be so kind as to respond with your thoughts it would be most appreciated.
 Jim S,
 Summerfield, FL (but currently on the road)"
 
Here are the pictures Jim Sent

 First I have to say, I wish everyone sending pictures of a tire condition took as good pictures as Jim did.
Well lit and close enough to clearly see the condition in question.
Anyway, here was  my reply:
" Jim,  Glad you enjoyed the seminar. Yes that is classical "Rivering". This is not something that only happens to Goodyear tires but is also seen on other brands. Its also not seen on all Goodyears either. It is a combination of tread pattern (design) and the selection of components and materials for the tire specification and the suspension characteristics of the vehicle. We design engineers do work at avoiding it but it is something that doesn't normally show up in our accelerated testing early in the design process so sometimes we can not "fix" it.

In my opinion, it is not a safety concern, but just a wear issue.
The best thing you could do is to swap out the two fronts for one of the set of duals. Now you do need to confirm the OD of the two tires going on as a set of duals is within 1/4".  The best way to confirm that is to measure the Outside Circumference while fully inflated and confirm the OC is within 3/4" of each other. Do the measurement before any tire dismounting is done to save $.
I don't know what wheels you have and sometimes you need to swap wheels sometimes not when moving from front to back.
I did a post or two on my blog and even a YouTube video on RVTravel channel on the topic and importance of matching duals. Just select from the list of "labels" displayed on the right side of my blog page for all the posts concerning DUALS.
Normally "Big Rigs" do not need tire rotation but this is one of the few times it is the correct course of action.

Hope this helps."


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Friday, August 22, 2014

How to weigh your RV for free

If you live in or travel through Oregon you can check the load on each axle and even get an approximation on your individual corner weights. I did this myself last week.

There are many truck scales across the state that are open and the electronic scale are left on after hours. You simply drive onto the pad and read the total load for that axle on the display panel located on a post about 40' ahead of you.

Now if there are no trucks using the scale you may be able to simply swing around or back up and get just the right side tire loads for each axle. With those figures its easy to subtract and get the approximate load on the left side positions.

See it in this picture where I am getting the weight on my Right Rear duals.

I say "approximate" as unlike the scale set-up used by RVSEF there will be a slight tilt away from the scale pad but I would think you should be within a couple percent of the actual side-to-side load distribution. I am pretty confident that most of you will have figures that are closer to the actual side-to-side weight distribution than just assuming you have a 50/50 side-to-side split on each axle.

With the individual corner loading you can then use the published Load/Inflation tables from your tire manufacturer company to learn the MINIMUM inflation you need based on the heavy side loads. Then simply add 10% to that inflation number for your "inflation margin" and you should be good to go. At least till you get on real, properly set-up individual RV corner weight scales.

Now I admit I do not know which other states provide this safety service to motorists, truck and RV owners, but for folks on the far west coast this is a great deal, at least till you are able to get the actual corner weights of your RV, or individual tire loads for trailers, confirmed by RVSEF.

If you know of another state that has scales available to the public as Oregon does, please post in the comments below as this information will help your fellow RVers


EDIT AND UPDATE   8/25/14
This post relates to Motorized RVs NOT Towables. Trailers have SPECIAL considerations for setting the inflation that I cover in THIS post.


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