Billionaire corporate raider Carl Icahn is trying to stop the planned sale of Philadelphia's iconic Pep Boys - Manny, Moe & Jack auto-repair chain with a richer offer of his own.

Japan-based Bridgestone Corp., which runs 2,200 Firestone tire and repair garages from offices in Nashville, agreed in October to pay $15 a share, or $835 million, for the 800 Pep Boys retail auto-parts stores and garages, and the company's corporate-vehicle and tire services.

But on Monday, with Bridgestone's bankers still hooking up financing and checking Pep Boys' books, Icahn's firm said he was ready to pay $15.50 a share, or $863 million - cash today, no questions asked.

Icahn's new offer "is clearly superior" to the Bridgestone deal, Keith Cozza, who runs Icahn Enterprises L.P., wrote in his letter to Pep Boys bosses Monday.

Pep Boys and Bridgestone did not immediately reply to Icahn's new offer.

In a sign investors hope someone will bid the price up further, Pep Boys closed at $16.06, an eight-year high and a premium to Icahn's offer.

On Friday, Icahn said he had purchased about one-eighth of Pep Boys' shares and that he hoped to add Pep Boys' retail stores to Auto Plus, a parts chain he controls.

After the stock market closed Monday, Pep Boys reported sales for the three months ended Oct. 31. Revenues slipped 2 percent, to $508 million, with both store and service sales down. Profits rose to $1.3 million from a loss of $2 million, although those results were juiced by the sale of two store locations for a total of $6 million.

Pep Boys sales have been flat, around $2.1 billion a year, and its profitability has fallen since 2010. As Americans bought more cars than ever in the last two years, fewer people have been buying its do-it-yourself repair products, the company told investors in September.

In September, the company said retail parts stores account for just 20 percent of its sales. Pep Boys says tires, garage service, and corporate auto fleet work represent a more promising future.

Before Icahn sweetened his price, Pep Boys said in a statement early Monday that Icahn had offered just $13.50 a share for the whole company in October, after six months of negotiations. Pep Boys picked Bridgestone's offer instead.

In that statement, Pep Boys added that Icahn appeared to be stepping in front of the Bridgestone deal to gain "negotiating leverage" so he might strike a lower price for Pep Boys' stores and add them to his Auto Plus chain.

"He's trying to [pressure] Bridgestone into paying more money," said Robert Costello, head of $100 million-asset Costello Asset Management, in Huntingdon Valley. "Icahn buys and sells a lot of companies. I don't think he is going to stay in this business long-term."

Costello says a higher price is likely to translate to bigger cost cuts at Pep Boys headquarters on Allegheny Avenue, which employs around 500, once a deal is done. He said the buyer will face stiff competition from rivals like AutoZone in a slow-growing do-it-yourself repair market, Costello added.

Icahn, 79, controls publicly traded Icahn Enterprises, which owns large blocks of shares in Apple, PayPal, and equipment manufacturers Hologic (X-ray), Nuance Communications (speech recognition), and Cheniere Energy (liquefied natural gas terminals), among others.