Yes but this was the exact reason why Ford and Firestone had a problem a few years ago. They had the smaller Ranger type of vehicles rolling over and too many folks were killed or hurt quite bad. Ford had around 26lbs written on the sticker and Firestone said 35lbs is needed. All of these accidents were in the Southern States where the road surfaces are much hotter the majority of the time. With only 26lbs in them they soon overheated and blew out usually on the drivers rear wheel. Ford has been paying for this problem ever since and will for many years to come as well.
Where to start?
First, it wasn't Rangers (pickup), it was Explorers (SUV). Interestingly, the same Firestone tire was on the Ranger, and they didn't show the same level of failure, and in particular, the rollover rate was extremely different.
Second, Firestone was the primary source of the problem. Their own data showed a dramatic difference to other designs and a dramatic difference to other factories. The true reason for the elevated rate of failure was more in the design of the tire, but clearly the factory processes were contributing.
But the issue you bring up is about reserve capacity - the amount of extra load capacity that a bit more inflation pressure provides. Ford said you didn't need any, Firestone disagreed. It could be argued that the vehicle operators were partially to blame because they didn't maintain the pressure.
Just to be clear, not ALL of the tires came from hot states, but the return pattern was mostly from hot states. It's the same pattern experienced by every tire manufacturer, it's just that the rates were different.
But the lessons learned from this situation were:
1) Reserve capacity. Notice that newer vehicle models are using larger tires than their predecessors.
2) Tire Pressure Monitoring Systems . They will become standard equipment. I'm thinking the original compliance date was the 2006MY, but that is obviously wrong (or more likely has been changed). Maybe its 2008MY?
3) Government regulations needed to be updated.
4) Tire manufacturers needed to improve tire performance in hot weather.
Which brings us back to the original question. Tire manufacturer recommendation or vehicle manufacturer recommendation?
Clearly what is on the sidewall of the tire is a maximum. Clearly what is on the placard has enough load capacity (Otherwise there would be a recall, and there have been some for this!).
So how is an uninformed person supposed to know what to use?
Every answer ought to reference the placard as it's the only thing that considers the vehicle's weight and potential loading.
However, a few extra psi wouldn't hurt! That has been my recommendation for any years, but I am currently changing that to say that some of the newer vehicles have this extra psi factored in.
Hope this helps.
