[Phyton]

We have a motorhome and I would love to tow our 2001 Prius behind it using a dolly. In other words, the front tires would be completely off the pavement at all times. Only the rear tires would roll down the highway.

The reason I have not done this (yet) is that it is apparently a violation of the warranty, but I don't see any way that it could hurt the car if the "drive " wheels aren't on the pavement. Any comments or suggestions (particularly from you auto engineering types)?

Thanks!

 

[john1701a]

> apparently a violation of the warranty

The only concern I've ever heard was if the front wheels were NOT off the ground.

The back wheels are nothing but drones, no purpose other than just holding up the car and providing some braking assistance. So they don't even pocess a way of harming the hybrid system.

 

[mrv]

towing

> apparently a violation of the warranty

The only concern I've ever heard was if the front wheels were NOT off the ground.

The back wheels are nothing but drones, no purpose other than just holding up the car and providing some braking assistance. So they don't even pocess a way of harming the hybrid system.

How interesting...

The Owner's Manual states to tow
using a flatbed or with the front
wheels off the ground. (Don't have
my manual handy to show the page.)

However, we do know that the Prius
doesn't much like 2-wheel dynometer
tests (often used for emissions testing
with only the front wheels on rollers) -
the Prius thinks that the wheels are
slipping (front faster than rear) and
throws on the pseudo-traction-control
and slows down the front wheels (to
match the rear). <shrug> But I don't expect that to be a problem if the car is off.

The thing to note is that the owner's
manual explicitly says not to tow
anything (like a trailer) with the
Prius. The owner's manual does
state the proper ways to tow a
Prius behind another vehicle (like
a tow truck or a RV/camper).

 

[Dick Larimore]

OK to tow

You are absolutely correct to think that using a dolly will not damage the Prius. The only thing that you are wearing out while towing the Prius with the rear wheels on the ground are the wheel bearings. As long as the front wheels are not rolling, you are OK. Make sure that the parking brake is not set. Absolutely, never tow the Prius with the front wheels on the ground.

 

[cpdutch]

Can you please explain the technical reason why the Prius should not be towed with the front wheels on the ground?

 

[RSnyder]

Can you please explain the technical reason why the Prius should not be towed with the front wheels on the ground?

Here's three possible reasons, none of them always apply, but Toyota lawyers probably just want to avoid all possibility of bad things(TM) happening:

Since the gas engine is off (RPM is 0), MG1 will be spinning quite rapidly. If you accidently exceed 42 MPH, it will be spinning too rapidly and could self destruct.

Both motor generators will be generating some pretty high voltage. Since there's usually no complete circuits, it won't act as a brake, so normally this wouldn't be a problem. But there's no computer monitoring the HV, so it's not quite as safe. Also, if you're towing because the Prius was in an accident, there might just be a complete circuit hiding somewhere.

If you're towing backward (most likely if the back wheels are off the ground), there will be a backward force on the gas engine. With its low compression, it might start slowly turning backward which is probably not good for it.