jasonsstover
Ohio
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Mods, not sure where this should go. Please adjust accordingly. Thanks.
Read a thread in the TT section about tire load ratings. "C", "D", etc. The differentiator I see is by how much pressure you can put in the tire, not by load weight. As a noob, what am I missing. Let's say you have a TT with an all-in max GVWR at 3500lbs, wouldn't you want to err on the side of caution and spend the extra few bucks for higher weighted tires? Is there a guide for what a C can carry and what a D, etc can carry?
Thanks.
Moved to Tech Issues forum from DIY
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donn0128
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In reality all you need is a tire rated for exactly half of the axle rating. If you have wheels that are rated for higher air pressure is sure is nice to spend a few dollars extra and get tires rated for more load. But some will tell you overkill. Do what you and your pocketbook can handle and be safe.
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ktmrfs
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jasonsstover wrote:Mods, not sure where this should go. Please adjust accordingly. Thanks.
Read a thread in the TT section about tire load ratings. "C", "D", etc. The differentiator I see is by how much pressure you can put in the tire, not by load weight. As a noob, what am I missing. Let's say you have a TT with an all-in max GVWR at 3500lbs, wouldn't you want to err on the side of caution and spend the extra few bucks for higher weighted tires? Is there a guide for what a C can carry and what a D, etc can carry?
Thanks.
load rating and pressure generally go hand in hand. LRC tires are generally listed at 45psi max, LRD 65psi max, LRE 85psi max. there may be some exceptions, but I haven't seen any. and for the same size the max load increases significantly as you go up in load rating. what a "c" or "d" can carry is dependent on tire size (cross section and diameter) and pressure. don't have a web site handy, but if you go to goodyear, maxxis etc. websites they will have a page giving the carrying capacity of their tires.
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amxpress
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Per your request:
Tire Pressure/Load range chart
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Chuck&Gail
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Two other points many neglect. RIMS have ratings, usually stamped on rear, or in valley under the tire. So if your TT came with LR-C tires, it likely (but check to be sure) has LR-C rated rims. Fully inflating LR-D tires on those rims is a THIRTY PERCENT OVERLOAD. Not what I call safe.
Also certain size tires require certain rim widths. For example most ST205/75R15's are on 5 or 5.5" wide rims (inside bead to beam measurement). ST225/75R15's require a 6" minimum rim width. Obviously it isn't safe to just change tire WIDTHS without checking rim widths first.
It really isn't as simple as it first appears, but those are the big tire/wheel concerns.
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CapriRacer
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2 thoughts:
The chart amxpress linked to is a MINIMUM. You'll want to use more inflation pressure (and therefore have more load carrying capacity) than what the chart says.
Personally, I think a 15% reserve (unused) capacity is what is needed to prevent failures in ST type tires.
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Uncle Wiggly
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CapriRacer wrote:The chart amxpress linked to is a MINIMUM.
Actually, the chart is for information, telling the following: For that manufacturer, a tire of a given size on the chart is rated at the load stated for the pressure indicated.
Generally, inflating the tire according to the load it will carry is better for the tire than using max pressure - better impact resistance and traction.
However, the best rule is to use the inflation stated by the trailer manufacturer. That may or may not be the max pressure indicated on the tire sidewall.
This is true for tow vehicles as well.
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FastEagle
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Many of the Special Trailer (ST) tire manufacturers require their tires to be aired to the maximum amount of pressure molded into the sidewall. They will not provide graduated load inflation charts, only the maximum required as depicted in the following reference.
Tire Chart
Maxxis - load inflation chart posted above by another poster - allows manipulation of the air pressure to set load capacities but they only support what the vehicle manufacturer recommends.
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ExRocketScientist
Laurel, MD
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If you take a look at CapriRacer's website, he cites an incomplete study that indicates it may not be such a good idea to use those inflation charts to air a tire less than the max stated on the sidewall. He is an actively employeed engineer in the tire industry, and I give a lot of weight to his two recommendations.
* This post was
edited 02/07/12 11:58am by ExRocketScientist *
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jasonsstover
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All, thank you for your responses. A specific example question: On this chart I will use the last line. If I have an ST235/80R16 and am running 50PSI, the load for that individual tire is 2600lbs. So, for example purposes, if I tow a Jayco 145RB with a GVWR of 2950, then I am well(huge overstatement) inside the comfort zone. A better choice might be the ST205/75R14 at 50PSI?
Thanks! I think I am over thinking all of this, but i would rather be overkill safe than sorry.
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