What sound does a semi truck make if you were going to write it down. Beep beep is what sound i think a car makes. A little help here. Thanks.?

What sound does a semi truck make if you were going to write it down. Beep beep is what sound i think a car makes. A little help here. Thanks.?
I think it should be vroom vroom. There are several onomatopoeias for it.