Ask him about all the details, which brands he has? prices? Fresh import? smuggled / non-smuggled factors, etc.?
1st ask all relevant details, and only then visit. If possible, and he is willing to ship the tyres to your place / city, etc. then it would be best, still, I am of the opinion that before buying anything (be it car, tyres, etc.), its best to have some physical inspection and verification of that item(s) personally.
If not satisfied, then Arshad Sb. a.k.a. @tintin1 also knows dozens of shops, and can assist and guide you, but before buying, 1st verify everything yourself too.
I hope, all of this helps and guides. Thank you.