Trailering 101


TIRE SIZE: Can it make a difference?

DISCLAIMER:  Always read all operating manuals, for tow vehicle, trailer, hitch and related components for towing suitability and compatibility before operating.

  In our continuing education of towing vehicles and their capacities we came across something we thought we would like to  share, since It can make a difference.

In our travels and customer relations, we have gathered a few brochures published by manufacturers relating to towing.  Some of them are extremely detailed and very straight forward, laying out gooseneck vs. bumper pull towing weights and the coinciding vehicle specifications  like: engine size, cab style, transmission type, axle ratio and surprisingly, TIRE SIZE.  These charts are very easy to read, but you need to read the entire chart even the little (*) footnoted items.   When reading one of these footnotes on a large SUV and even a 1/2 ton truck we found that the customers had a choice between a 16" and 17" tire.  What was surprising, sort of, was that the exact same vehicle with different sized tires had different towing capacities. And if you haven't guessed it already, the SMALLER tire had the higher rating, by 400 to 500 lbs depending on the vehicle.  Could this make a difference to the buyer/already owner?, maybe depending on the type of trailer you intend to tow.

Now you may be asking why is this?  To give you a non-mechanical, non-scientific explanation we believe it goes back to the "10 speed up a hill" analogy which we use often to help folks make sense of "axle ratios".   Basically, if you are heading up a large hill on a bike in tenth gear, there won't be many revolutions required by the peddles to get to the top. BUT, your going to work really hard to get it there.  Now, If you put that same bike, on that same hill in a lower gear, like 1st, the peddles will make several revolutions but you won't work any where near as hard to get to the top. So what does that have to do with tires? We believe by increasing the tire size you are once again making fewer revolutions, working a bit harder, and in turn lowering your towing capacity. (For those technical types out there, we are sure there is a much more complicated explanation, but for our purposes, we are just trying to make a complicated issue a bit easier to understand.)  NOTE: With "axle ratio", the higher the number the more revolutions it makes and in turn working less and pulling more. 

As usual, we are sure there some exceptions to the above.  However, once again we just want to make you aware of this issue, and you can at least ask the questions.

Happy Trailering... See you Next Month. (Or whenever we feel like something needs to be said.)

BACK

TOP

FORWARD

If you have any comments, suggestions or topics for a "Trailering 101" article we'd be happy to take them.  Trailering education is our goal.