Bridgestone Corp. will decide by the end of the year whether to top Carl Icahn's bid for Pep Boys after the billionaire investor raised his offer for the car-parts chain to more than $1 billion.

The Japanese tire maker will decide its next move within three business days, spokesman Fusamaro Iijima said Tuesday in an email.

Hours earlier, Icahn Enterprises escalated a bidding war with an $18.50-a-share cash proposal, which it said it will be willing to boost even further if Pep Boys does not increase the termination fee in its deal with Bridgestone.