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09-01-2013, 03:01 PM
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#1
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Senior Member
Join Date: Apr 2008
Location: Long Island (Nassau County), NY
Posts: 4,352
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Strange tire wear pattern
I noticed a strange wear pattern on the front tires of my 2008 Berkshire 390BH. There seems to be a small, concave 'groove' that is wearing on the inside and outside edges. I thought that it might be under-inflation, but according to the charts, I am right at the recommended pressures for the weight on the tires (LF tire is at 97 lbs, weight is 4830, RF tire is at 96 lbs, weight is 4510). Not sure why the tire is wearing this way. Any ideas?
Thanks,
Tom
I have attached pictures that I hope will show what I am trying to describe. Tires are Michelins 255-80x22.5.
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Tom and Margaret
2014 Berkshire 390bh-60
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09-01-2013, 03:47 PM
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#2
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Mod free 5er
Join Date: Mar 2008
Location: Concord, NC
Posts: 24,702
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Wear on both edges of tires is an indication of under inflation regardless of what charts say about tire pressure vs load.
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09-01-2013, 03:50 PM
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#3
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Senior Member
Join Date: Apr 2008
Location: Long Island (Nassau County), NY
Posts: 4,352
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If you don't use the weight/pressure charts, how do you determine the pressures for the tires?
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Tom and Margaret
2014 Berkshire 390bh-60
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09-01-2013, 04:10 PM
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#4
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Mod free 5er
Join Date: Mar 2008
Location: Concord, NC
Posts: 24,702
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Quote:
Originally Posted by tmmar
If you don't use the weight/pressure charts, how do you determine the pressures for the tires?
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It is a good starting point, but as you are experiencing, you are wearing the outside and inside edges of both tires indicating under inflation. If it were me, I would increase both front tires by at least 15# or to be safe and to even out the wear, inflate to whatever the max sidewall pressure says.
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09-01-2013, 05:01 PM
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#5
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Phat Phrog Stunt Crew
Join Date: Jun 2012
Location: Biloxi, Ms
Posts: 705
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Here is a pic of over and under inflated tires OC is dead on!!
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Wayne & Susan Biloxi,Ms
2012 GeorgeTown 351DS...2015 Ford Focus/Brake Buddy
FROG Member
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09-01-2013, 05:29 PM
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#6
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Senior Member
Join Date: Oct 2010
Posts: 277
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it may be that the pressure gauge you are using i out of calibration or the weight is greater than thought
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PT Avenger 33BHS-TE
2020 f-250
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09-01-2013, 05:41 PM
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#7
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Senior Member
Join Date: Apr 2008
Location: Long Island (Nassau County), NY
Posts: 4,352
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Quote:
Originally Posted by awwall
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awwall,
I see where the tread wear pattern for under inflation involves the outside edge of the tire. However, the tread wear on my tires shows just a small, concave area along the edge. Not the entire outside edge as shown for under inflation.
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Tom and Margaret
2014 Berkshire 390bh-60
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09-01-2013, 06:06 PM
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#8
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Commercial Member
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,889
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There are numerous posts on tire inflation in these threads.
Here is one such post.
Many who are posting are providing answers based on their personal experience or what they have heard round the campfire.
As a Tire Engineer i would like to provide a slightly different perspective. One based on 40 years experience working for a major mfg. as many posts by non-engineers are not completely correct.
Your motorhome should have certification label ( tire placard) that the RV manufacturer applied to the vehicle. This
Here is a post on my blog on load & inflation
Also on gauge accuracy
The basic answer is that for motorhomes you need at least enough inflation pressure to carry the actual load on the tires.
Trailers should use the inflation on the tire because of unique side loading of tandem axles.
Until you get the real loading on each corner of your RV I strongly suggest you set your cold inflation to the inflation on the placard or 5 to 10 psi higher but not exceeding the inflation molded onto the tire.
tmmar
Do you have any idea what your actual tire loading is? You provided the tire size but not the Load Range. Also what are the axle ratings on your placard. GAWR Front & GAWR Rear and what inflation F & R are shown on your placard? Having this information makes providing accurate answers easier.
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.Write a blog on RV tire application RV Tire Safety. 48 years experience as tire design & forensic engineer. My RV Freelander 23QB on Chevy 4500 chassis. Giving seminars on RV Tire applications (not selling)@ FMCA Conventions. Mar 20-22 Tucson AZ
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09-01-2013, 06:08 PM
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#9
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Commercial Member
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,889
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Quote:
Originally Posted by tmmar
awwall,
I see where the tread wear pattern for under inflation involves the outside edge of the tire. However, the tread wear on my tires shows just a small, concave area along the edge. Not the entire outside edge as shown for under inflation.
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You take good in-focus pictures. Can you get one looking over the tread (similar to that seen in the drawings) not from the side?
There are a couple different types of circumferential wear with different causes. I really don't like guessing.
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.Write a blog on RV tire application RV Tire Safety. 48 years experience as tire design & forensic engineer. My RV Freelander 23QB on Chevy 4500 chassis. Giving seminars on RV Tire applications (not selling)@ FMCA Conventions. Mar 20-22 Tucson AZ
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09-01-2013, 06:22 PM
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#10
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Senior Member
Join Date: Apr 2008
Location: Long Island (Nassau County), NY
Posts: 4,352
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Tireman9,
Dark and cloudy now but hopefully it will be nicer tomorrow (although the forecast is for cloudy and rain). The loading on the left front is 4830 lbs and the right front is 4510.
Tom
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Tom and Margaret
2014 Berkshire 390bh-60
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09-01-2013, 06:32 PM
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#11
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Senior Member
Join Date: Nov 2012
Location: Home is where I park it
Posts: 1,503
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Quote:
Originally Posted by tmmar
Tireman9,
Dark and cloudy now but hopefully it will be nicer tomorrow (although the forecast is for cloudy and rain). The loading on the left front is 4830 lbs and the right front is 4510.
Tom
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Also, Tireman...... I've been told that all tires on the same axle have the same pressure, regardless of the individual wheel weights. True or False?? Enquiring minds want to know.
Boowho??
P.S. "You da man" when it comes to tires. Your credentials are impressive. I also notice you are from Akron.
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09-02-2013, 09:40 AM
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#12
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Senior Member
Join Date: Apr 2008
Location: Long Island (Nassau County), NY
Posts: 4,352
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Quote:
Originally Posted by boowho
Also, Tireman...... I've been told that all tires on the same axle have the same pressure, regardless of the individual wheel weights. True or False?? Enquiring minds want to know.
Boowho??
P.S. "You da man" when it comes to tires. Your credentials are impressive. I also notice you are from Akron.
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I was also under the same impression that Boo stated that tires on the same axle have the same pressure. If you could verify if this is true or if it is not it would be appreciated.
I also agree with Boo's statement about you being the tire expert here.
Thanks for your input.
Tom
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Tom and Margaret
2014 Berkshire 390bh-60
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09-02-2013, 11:58 AM
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#13
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Commercial Member
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,889
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tmmar & boowho
Yes all tires on any axle should have the same inflation.
For motorhomes like immar's that would mean his minimum inflation should be capable of handling 4830.
For motorhomes, Look up your size in the tire mfg's load/infl table and find the inflation that is rated for 4830 or more. That would eb your MINIMUM cold inflation. I suggest you add about 10% to that so you don't have to mess with adjusting inflation when the ambient temp changes.
Don't exceed the rating for the wheels.
For multi axle TT I suggest you run the inflation molded on the tire. This will help decrease the internal structural loads that are trying to tear the tire apart.
Different loading dynamics need different solutions. Most of the published information is based on old single axle TT.
TT owners might want to read THIS post.
General info on Inflation HERE and HERE.
__________________
.Write a blog on RV tire application RV Tire Safety. 48 years experience as tire design & forensic engineer. My RV Freelander 23QB on Chevy 4500 chassis. Giving seminars on RV Tire applications (not selling)@ FMCA Conventions. Mar 20-22 Tucson AZ
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