I don't think it's true. I have been with some fat chicks who were rather tight. Admittedly I gauged this by look and fingering. I didn't attempt to have sex with these females because I figured I wouldn't fit and it would be too painful for them for me to try and work my cock in. Instead we 69-ed and I got some of the best head of my life. I know that sounds arrogant and egotistical, but this is large penis support group. (I'm sure some of you have had those nights where you tried every which way and used a lot of lube but it still hurt the woman so you stopped because what's the point of fucking someone if it's going to hurt them and not be pleasurable.)
But the biggest chick I was ever with was over 200 lbs. and she had the widest vagina I'd ever seen. It was the circumference of a golf ball. After having gone through a string of tight pussies that, while fun, I had a hard time initially penetrating, this was a breath of fresh air. I didn't have a condom with me and I was planning on just doing some straightforward 69-ing throughout the night. And I don't know if I was hallucinating from having stared at her upside down pussy hole for so long, but I swear to G-d I thought it was 'winking' at me as if to say, "Come on you know you want to stick your dick inside of me." So I said, "That's it, I have no condom, but pleeeaaassseee can I put it inside of you because your pussy is the perfect size for my cock." She said, "I've been thinking the same thing for the past half hour I've had you in my mouth." I slipped inside of her with no resistance at all, but it still had enough grip to get my cum rising. Some of you talked about 'bottoming out.' I'm 7 '' long and at first that didn't happen, but at one point when she put her knees to her ears I did bottom out. Interestingly, her cervix must have had a lot of nerve endings around it because after the second 'bump' she moaned, "I'm cumming!" In addition to my cock giving her tremendous stimulation against her cervix, this deepest patch of tissue felt absolutely amazing against my cock. I grazed it two more times after she made her announcement, and then I made my own announcement ... "you're not the only one." I pulled out and unloaded on her mammoth tits.