Actually, that's for the 235/35R20. The 225/35R20 is load rated 90.
And for the record, while there may now be a "safe" application of 20s on a 6, that still doesn't make it a smart thing to do. Blue70's setup, for instance, adds 7 lbs. (28 lbs wheel, 22 lbs tire) of unsprung weight to each corner. IIRC, for each 1 lb. of unsprung weight you add, it's like adding 8 lbs. of vehicle weight. So, Blue70 has, in effect, added an extra 224 lbs. of weight to his vehicle. That has to have negative effects on fuel economy, handling and performance, not to mention the added stress to the rotors (which may result in premature warpage) and increased risk of sidewall and wheel damage due to less impact protection. It may look cool, but it's still not a smart move, especially where performance is concerned.
Back when I first put 315/35/17's on my 03 Mustang you could feel the difference... the extra weight slowed how quick the car would accelerate.
(A set of 4.10s and a supercharger fixd that
But then again I will never be any where near within 224lbs of the max weight the car was designed for, so I'd say I am still good
(I have had my wife in the car once in the month I've owned it :P )
I'm sorry and I don't want to ruffle any feathers, but I don't consider a 6 (or at least my 6) a performance vehicle...
I just had a son and needed a family car with 4 doors and I thought someone did a decent job with all the extras that came on my car.. If I was looking for performance I would have kept looking