Question: We were invited to friends out of town for Shabbos, though our hosts told us that we weren’t allowed to travel on Friday afternoon. Is that right?
Answer: Rambam (Shabbos 30:11) writes that one mustn’t travel more than 3 parsa (approximately 7.5 miles) on Friday as their hosts (or own family) may not have had enough time to prepare for them. The Shulchan Aruch (OC 249:1) writes that if one is expected and no further preparations are needed, however, then they may travel further.
The Shulchan Aruch Harav (OC 249:3) and R’ Ovadia Yosef (Yabia Omer 2 OC 14:6) write that this limit applies to one walking. One travelling by other means has as long as it takes to walk this distance, or 3 hours and 36 minutes (See Shulchan Aruch OC 459:2).The Mishna Berura (249:3) writes that while many aren’t as concerned about this halacha nowadays, we need to ensure not to arrive too close to Shabbos. Likewise, R’ Yehoshua Neuwirth (Shemiras Shabbos Kehilchasa 42:24) writes that as travelling late in the afternoon may lead to chilul Shabbos, one should plan to arrive in good time before Shabbos and prepare for any eventuality.
In conclusion, one should avoid travelling on erev Shabbos unless is one is sure that they will arrive in good time before Shabbos.