What the guys are saying is that, yes you can put stickers on your car, but technically they won't be sponsors. You'll just be giving them free advertising space.
Sponsors pay towards your running costs in return for advertising their companies on your car in front of crowds of people at racetracks etc.
I was just clarifying the use of the word sponsor, nothing else
If you'd managed to secure hankook sponsorship I'd have been massively jealous
*No offence to Tarmac*