But wouldn't Kratos without the gear be a good deal weaker? He was in the first Thor fight, it's why he had so much trouble, when he had decent equipment he didn't have that much trouble with Thor. I still think Tyr is really strong, but sometimes I don't know how accurate Kratos's statements are, the codex included, Kratos seems to downplay himself a lot, like when he says Freya might have beaten him, or how he would need Atreus to beat Thor, I think he is just too humble most of the time, not that Freya, Thor and Tyr aren't strong, as they are some of the strongest Norse Gods.
It's also worth noting that Kratos seems to be comparing them to his base self and not enraged self, and while the mural indicated he'd lose if he was bloodlusted, it's unclear as to how, we know Kratos is stronger in Rage mode, gameplay and lore wise, so how would he lose to Thor if he was truly enraged? Odin showing up and helping Thor is more what I thought would have happened to beat Kratos, but we can't know for sure. Also, Kratos doesn't even his best gear or magics from Olympus as he points out, so who knows how strong he'd be if he did.
All that being said, I'd probably still put Tyr at Thor level bare minimum, I might even have him slightly higher due to better versatility and skill. He's probably only slightly weaker and slower, which I think his skill and various magics could make up for.