Weight limits...what happens if exceeded?

Five people approaching 1000 lbs may be a bit snug in the back seat.

The car will be fine. But you could take a big hit in MPG.

So if you buy anything on your shopping trip, where will you put it?

 

What will happen? While you are flagrantly violating the speed limit in sizzling summer temperatures with defective underinflated tires that are technically undersized for your poorly-suspensioned vehicle, the left rear tire might suffer a blowout, rolling the vehicle and killing you. Oh, nevermind, that was a 1990's SUV.

On one hand, exceeding the car's load rating reduces safety margins. On the other, very few people even have a clue about their vehicle load ratings, and regular exceed them. Especially on larger SUVs whose load capacity didn't increase proportionately with their cargo volume. As the Firestone/Explorer fiasco showed, it took many simultaneous problems stacked on top each other before the failure rate increased enough to be detectable. Remove some of those problems, and the risk from the rest is likely so small it will be difficult to detect. This isn't commercial aviation, the standard traffic risk of simply being on the highway is much much higher.

The Prius load limit is in the typical range for cars its size. While you will be able to find midsize cars with 900+ pound load ratings, a 1000 pound rating will be tough to find.

If this risk still concerns you, look at the pool of available vehicles among your friends, and lean towards the largest and newest car. While balancing tradeoffs, beware that older vehicles of any size have weaker crash safety designs, and that full size SUVs will bring higher load ratings but weaker crash safety standards and poorer handling and crash avoidance characteristics.

You have no zero-risk choices. Even skipping the shopping trip is not zero-risk. Life is short. Whatever vehicle you take, make sure the tires are in good condition and fully inflated, and enjoy the shopping.

 

Mainly, be careful traversing speed bumps, as you will have less ground clearance.

 

As I found out overloading my Ford Mondeo Wagon hauling garden-tiles (~1300lb of tiles + driver equals 400lb+ over the limit)... trailerhitch screws scraped the tarmac after a bump in the road

 

We here have no way of knowing the criteria that Toyota uses in specifying its weight limits. Is it actual axle capacity or some slight or notable change in handling, perhaps due to increased body roll while cornering? I would say that you're OK for local lower speed travel, but if you're driving down an interstate and have to do an accident avoidance maneuver, you are conducting an experiment.

P.S. I have bottomed out the rear suspension (2010 Prius) driving with 5 adult passengers on undulating roads. There was no adverse effect but the jerk was very apparent (jerk is a technical term).

 

Inflate the tires to a higher PSI. DO NOT exceed the "maximum inflation pressure" on the sidewall. When the tires are at 70F you may inflate to that "maximum inflation pressure". If it's colder when you put air in them then you have a safety margin.

Be aware your stopping distance will be much longer. It could be twice what it is with only you in the car. So in an emergency stop.....

Don't travel at the crazy speeds some on the roads go. Stay well within the limits.

If the road is rough, SLOW DOWN!

Follow those simple rules and you should be fine.

 

With three large people in the rear seat....be careful that no ones "cheek" obstructs the battery cooling inlet!!

 

One of the biggest risks of overloading Prius is the increased braking distance. I had 5 adults in my '09 one time, (190+200+150+165+175) about 880 lbs. Went to stop suddenly in SF, slightly downhill. Only then I really experienced how much greater the braking distance was. Almost hit the car in front and almost got hit from behind.

Prius v is a solid bet for 5 larger adults since it's load rating is on par with midsize sedans like Camry.

 

Two words: Flaming Fireball.

Be sure to get video for the 'net. :madgrin:

 

Had that too in a Fiat 137 (iirc) with 5 adults. Drumbrakes all round.

Came up to a junction where I had to give right of way. Braked as there was traffic coming. Braked harder as I wasn't slowing down... Ended up sliding into the road just after the car who had right of way had passed me :rockon:

Simply very bad judgement on my part coupled with a lot of luck .

Something like this (same color, almost same body).


Damn, I am full of anecdotes... just let me know when to shut up...

 

OK - this is embarrassing. 1300+ pounds 438 miles on an emergency trip from Omaha to St Louis on a windy day in December - using crummy I-29 and I-70. MFD averaged 48 mpg.

No problemento.

 

1000 pounds of cargo is only 33% more mass than the car itself. It won't double the stopping distance.

 

It is a non-linear relationship. Ditto for speed vs braking distance.

 

Those of us that sometimes "overload" a Prius (Including me when bringing home gardening materials) should consider a shorter interval for engine (ICE) oil and ATF drain/refills.

I normally suggest doing the first ATF refresh at 30k miles and then every 60k miles thereafter which could be shortened to every 30k miles if you overload and are worried about damage to the gear train in the transmission (HSD).

I do engine oil changes every 5k miles in my 2004 Prius (Syn oil) and that should suffice. Those of you that follow the every 10k mile oil change policy could consider a shorter cycle if you carry heavy loads.

JeffD

 

Sources?

I'm very familiar with the basic mechanics equations. For a constant braking force, stopping distance is a quadratic function of speed, and a linear function of mass. By claiming that a thousand pounds will double the stopping distance, you are effectively claiming that the extra mass actually reduces the available braking force.

 

If you overload it, a voice comes onto the radio and says "This vehicle will self-destruct in 30 seconds."
:heh:

 

Fuzzy's math is of course correct. But as I sit here thinking about the influence of a passenger load, I'm realizing that a rather significant change is in the height of the CG (center of gravity) of the loaded vehicle. Just think of all the vehicle masses that are lower than passengers, e.g., wheels, brakes, drive axles, floor pan, traction battery, transaxle, and perhaps even the engine (with most of its steel at its bottom end). This change in CG height has to influence cornering.