They are not lying...to a point.
The Pirelli's on my Rivian, thru the Rivian forums, is a great tire, but need replacement inbetween 9k and 25k. They are stupid expensive at $529 a tire! These tires are rated as a 116H XL. I like them OK... They provide great traction on dry pavement, but are nearly useless on the snow, and hydroplane easily on the wet.
However, Michelins tires have all been EV rated for some years now, and the cost of them is a lot more reasonable. The Michelin Defender M/S2 are $335 and are rated as a 115H XL.
The Continental Terrain Contact A/T is NOT rated as a EV tire, are rated as a 115T XL, and are $311.
The Continental Terrain Contact H/T is also not rated as a EV tire, is the tire of choice by the Rivian community, is rated as a 115H XL. These cost $279.
Now comes the weird part... The owners that have switched to the Cont TC H/T are reporting a better/higher efficiency over the stock Pirelli's. No one that has switched to them has had to replace them for wearing out as of yet. One user is getting close, as he has 57k on his Rivian, and 45k of those are on the Continental's... And he is running the A/T model.
I am a Michelin supporter thru and thru. Have had nothing but a great experience with them on my Envoy, who is now on her 3rd set of them. I get about 70-75k out of them.
I am hoping the softer rubber that Michelin uses will provide a better ride on my Rivian.. I should be replacing them by Xmas if Rivian forums mileage use is a indicator.
Because my Rivian is a fat girl... we have to run the tire pressures up around 49-50 psi. Otherwise we end up like the Ford Explorer/Bridgestone fiasco years ago.