"1/2" links
McMaster-Carr
"1/2" links
McMaster-Carr
170 with tracks in near average 75 percent or more wear, get new chains. As JohnF wrote more less, simply chains stretch.
1/2 links will eat the sprocket and you'll be doing them also, you'll probably do that next time anyhow of they aren't sharp now.
Look at the chain specs your buying, some have 150 hour life some 400ish hour life.
My new beer holder spilled some on the trails - in it's hair and down it's throat.
Joe Camel never does that.
Advice is free, it's the application that costs.
Replace the front chains. Get a good quality chain off ebay, cheaper then buying new from a dealer. Look for Diamond or Tsubaki. Do not use a chain made china. Brand new front chains are very tight and a pain to install. Make sure you lube the chains with good quality lube. Dry chains wear out much faster.