Why would I pronounce "ally" as "alley"? I'm not ESL ????
Anyway why would I use the word "alley" to a tuk-tuk driver or indeed any other Thai person? It is called "Soi Rambuttri" in Thai so why would I try and confuse them? The transliteration of Rambuttri itself isn't tranny that close to the correct pronunciation so your just setting yourself up to fall by adding an unfamiliar English word at the end.
BTW calling a Soi an alley, or ally if you prefer, is not even that accurate. The Thai word "trok" is closer to the definition of an alley than "Soi".