Both are incorrect. Notice the difference in sentence grammar: Either road will lead to a parking lot. = If you take this road OR that toad, it will lead to a parking lot. Both roads lead to a parking lot. (No "will"!!) This is a statement of fact about the roads. There is no "if" meaning implied here. either = this on OR that one both = this one AND that one ...Hence the difference in sentence grammar.

Sorry, both are wrong. Either road leads to a parking lot. (or, "Either of them leads to a parking lot") - notice it's a singular form. You're looking at two separate options. Both roads lead to a parking lot. - plural form. You are looking at them collectively.

i can not underestand very good u speak but if i have 2 road i choice bettere rode BUT IF 2 ROAD IS GOOD I CHICE 2 RODE i go to 1 road and sea all parking and all car whene finish go back and choice othere road and sea like thise latere i think and choice thise parking have more old car beacuse my car is old and he like old fereind (: whene i back my car is very happy

hi my engelish is BAD(: i am new in italki i dont now how i can use ok i have 1 ask u give me massege?

Peachey's comment is well taken. At the same time, I think I understand Tommy's point of view. "How do I reach the parking lot? There are two roads. Which should I take?" "It doesn't matter. Choose either, because both of the roads lead to the parking lot." So Tommy has two statements, one using either and one using both, each with the same practical meaning.