Very disappointing snow experience

[zefram47]

I had a Plug-in-Prius with X-Ice winter tires that was way better in snow than our Expedition with AT tires.

This for sure. My Subaru STi on some cheap AF Hankook winter tires was an absolute tank compared to my 4Runner on Falken AT3W (3PMSF ATs). Some of it is the weight, but 3PMSF ATs are no replacement for real winter tires.

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[moosehead]

 

[kylealden]

R1T on 22" all-season tires

fin

 

[COdogman]

@moosehead begged Rivian until his knees bled to get you snow mode, so USE it. He also made me buy this sweater, which may or may not have helped push it over the finish line.

 

[ironpig]

Maybe your 22inch road tires are just not big enough for the snow, have you considered a Tahoe?

 

[kylealden]

With no connection between the wheels (the differential), the tendency is for both Wheels on the axle to slip on a quad motor Rivian. This will send you sideways.

The new snow mode seems to be a lot better, but because of the design, it will never be as good as having a differential.

Citation needed? This feels totally wrong. There is nothing about quad motor that should make it more likely to slip. Quite the contrary, a differential is going to naturally send torque to the wheel with least traction and needs mechanical braking (or lockers) to mitigate that by braking the wheel without traction (or forcing wheels to turn in sync).

A quad motor design can simply cut power to a wheel when it detects slip. In all cases you're depending on the wheel speed sensors to detect slip (or a manual lock). The differential approach adds constraints to what you can do at that point, not advantages. There's no intrinsic disadvantage to quad motors here. Maybe Rivian's implementation needs love (I certainly haven't had issues), but it's not a mechanical limitation.

 

[Dark-Fx]

Maybe your 22inch road tires are just not big enough for the snow, have you considered a Tahoe?

Good thinking. Actually these tires would fit on the Rivian if OP could find Rims.
https://www.tires-easy.com/275-25-28/delinte-tires/ds8/tirecode/805874

Edit: Found some that even sorta look like Rivian's design!
https://lexani.com/wheel/Lust

 

[R.I.P.]

Citation needed? This feels totally wrong. There is nothing about quad motor that should make it more likely to slip. Quite the contrary, a differential is going to naturally send torque to the wheel with least traction and needs mechanical braking (or lockers) to mitigate that by braking the wheel without traction (or forcing wheels to turn in sync).

A quad motor design can simply cut power to a wheel when it detects slip. In all cases you're depending on the wheel speed sensors to detect slip (or a manual lock). The differential approach adds constraints to what you can do at that point, not advantages. There's no intrinsic disadvantage to quad motors here. Maybe Rivian's implementation needs love (I certainly haven't had issues), but it's not a mechanical limitation.

To cut power to a wheel that is slipping, the wheel must first slip. The damage is done, you are going sideways at that point. I am in a off-roading group with a Rivian in it, many hundreds of hours of experience of how this works in the real world. The R1T does great in many scenarios, but in ultra-low traction, especially when on a side-hill, they are straight-up evil to drive.

 

[kylealden]

To cut power to a wheel that is slipping, the wheel must first slip.

This isn't any less true with an open diff than with an electric motor - an ICE vehicle with differentials has to detect and stop the slipping wheel via mechanical brakes.

The diff-based approach is just worse because it relies on mechanical intervention via the brakes and has extra layers of indirection and input lag between the motors and the wheel response.

 

[bjcleaver]

I also live in PC but I have the 20" wheels. The stock AT tires were fine but I got winter tires (Nokian LT3) put on last month and they make a huge difference. Driving yesterday in that mess of wet concrete snow, I was watching cars slip and slide all around me on as I cruised by. I can't imagine not having snow tires up here this winter with how much snow we've had to date, especially if you're driving the canyons or to the Cottonwoods.

Not sure if there are great winter tire options in the 22s?

 

[R.I.P.]

This isn't any less true with an open diff than with an electric motor - an ICE vehicle with differentials has to detect and stop the slipping wheel via mechanical brakes.

The diff-based approach is just worse because it relies on mechanical intervention via the brakes and has extra layers of indirection and input lag between the motors and the wheel response.

Actually, no. But sure not going to sit here in an internet forum & argue with you.

We take off for the trails @ 0600hrs most Sunday mornings out of Azalea, Oregon. We have 2 R1Ts in the group now; you are welcome to come out into the hills with us & lay your theories on as thick as you like.
?

 

[Tbirdjeff]

fin

No idea what that means

 

[Shzeph]

No idea what that means

Fin means “end” in Latin

 

[kylealden]

Fin means “end” in Latin

As in, "the end," as in, "the post probably could have ended here." ?

Not trying to razz too much, I know you acknowledged the tires were a limiting factor in your original post. But the disappointment really should begin and end there. No vehicle, let alone one as heavy as a Rivian, can overcome the wrong rubber in slippery conditions.

 

[kylealden]

(BTW/case in point - I've been pretty happy with the 20" ATs on packed snow in my winter driving so far, including some pretty hairy days, but I just swapped out for a set of Blizzak LTs for the rest of the season. If you drive in sub-freezing conditions often, winter tires are a good investment. And the cost isn't really a factor - you'd be wearing/replacing your OEM tires anyway. Just an extra tire swap once a year, but that's small beans at Rivian scale.)

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