Not sure if this is the right place to ask, but whatever.

I purchased a pair of 666-XHS a few years ago, and have worn them almost everyday with my Alpine Star Super Victories https://metroracing.com/products_item.php?p=1211

Anyways, I ordered them in a size 31 waist. Sizing chart says in reality it's a size 32, and description says it'll stretch an inch with wear.

However, I am considering ordering another pair of jeans, and I measured the waist of my 666's last night (yes, according to the Iron Heart way), and they've stretched to 35 inches! No wonder they're too loose for me now, I thought I was getting slimmer.

Anyways, is this normal? I have never washed nor soaked them, nor do I want to. My thighs are already getting too big for them (main reason I'm in the market for another pair of jeans). Should I take this stretching of three inches into consideration when purchasing, say, the 634-XHS?

Also, will a lighter fabric (18oz or something) stretch more? or possibly less?