Michelin tire blow out!!

Yes road crown and other factors can affect actual tire loads on duals.

Reason single vs dual tire psi/load ratings are different.
Effective in 1999, the Tire and Rim Association (TRA), which sets standards for load and inflation, decided to change the old system.

In early days, tires didn’t have different loads for single and dual use. Everybody assumed they would be the same. But, over time, manufacturers realized that the actual load on each tire in a dual assembly is rarely the same.

For one thing, the tires may not be equally worn.
If there’s a big difference in wear, there’s a difference in overall diameter.

The larger tire will carry more of the load.

Road crown also affects load. The inner tire of a dual assembly can be more heavily loaded than the outer one.
And, there are factors like camber that can also make the loads shared by the tires in a dual assembly different from each other.

Loads for tires in dual assemblies are set lower because the tires may not be loaded the same.

Unequal wear can cause unequal loads.


Road crown may put more load on the inner tire.


Excessive camber can cause unequal tire loading.





There is a lot going on with them dual wheel assemblies.

Scary stuff... glad it was all a happy ending. Glad to see that someone posted a link to what to the video of what to do if a front tire blows. I've watched it a few times, but hope that I am never tested to see if I remember it in an emergency.

So, Dennis, did you actually remember to keep your foot on the gas in the blowout crisis? I probably would freeze in the emergency - and hold the accelerator steady.

JaxDad wrote:

j-d wrote:
I maintain that the Right Rear Inner is the most abused of the six tires. Like its left inner partner, it bears a little more than its share of the load because the crown of the road gives the outers a little break.

I'm not quite sure about that, the crown of a 2 lane road runs from the centerline to the shoulder in a single run. In a divided (Interstate type highway) the slope is a single run from side to side.

There is never an instance where the crown is designed to be in the center of a vehicle.

Jaxdad didn't say that the road lane is crowned in its middle- I took his point to be that the (continuous) slope from the crown being high-to-low, it shifts weight from the crownside wheels to the shoulderside wheels. Might not be a LOT of weight, but I agree that it may be enough to make a difference over time.

j-d wrote:
I maintain that the Right Rear Inner is the most abused of the six tires. Like its left inner partner, it bears a little more than its share of the load because the crown of the road gives the outers a little break.

I'm not quite sure about that, the crown of a 2 lane road runs from the centerline to the shoulder in a single run. In a divided (Interstate type highway) the slope is a single run from side to side.

There is never an instance where the crown is designed to be in the center of a vehicle.

"We were very lucky in more than one aspect! Very fortunate that it was not a front tire blowout!! "

Time to repost the steer tire blowout video. Michelin has one that actually features a motorhome (same technique), but I like the one with my hero, Benny Parsons.

Steer Tire Blowout

I maintain that the Right Rear Inner is the most abused of the six tires. Like its left inner partner, it bears a little more than its share of the load because the crown of the road gives the outers a little break. It's also next to a hot brake. But the Right is usually near a hot exhaust.
***AND*** when we run the outer dual off of the pavement, the INNER bears all of the load on the passenger side of the axle. Sudden spot overloading, again and again...

looks like a impact blow out to me.Must have at some time ran over something and it finally gave out

Good outcome all the way around!!

Didn't know more tires (date codes??) had been added.

Hear that scratching sound? It's all the owners with Michelins scraping the ground going under to look at their sidewalls...