If I sell a vehicle prior to filing bankruptcy how much time must pass before the vehicle transaction is non-reversible in bankruptcy?

Such transfers may not effective to put your assets beyond the reach of creditors and bankruptcy trustees.  Worse, such action could also lead to the denial of the discharge.   

Generally, transfers within 90 days before the filing will be presumed to be fraudulent conveyances where the debtor did not get reasonably equivalent value for the asset or the transfer was made with the intent to hinder creditors.   However  transfers to "insiders", which includes relatives, made up to 1 year prior to the bankruptcy filing, may be avoided or undone.  Additionally, the "look back" period may be even longer under the law of your state.