Jorge Lorenzo said he had little choice but to use the harder tyre in Sunday's German MotoGP, having been told by Bridgestone that the softer option would be 'impossible to use'.

The Yamaha star said that Bridgestone felt that the softer rear, with which he had been much faster, would not last the race distance - the company appearing to fear a repeat of the chunking problems suffered at the previous Assen round.

"To be honest this weekend we've been very uncompetitive. Not fast in any practice with the hard tyre, that we had almost an obligation to use in the race, because Bridgestone told us that it was impossible to use the soft one," Lorenzo said.

"With the soft one I have been 1.5 seconds faster in the warm-up, but they told me it was impossible to use. That in the middle of the race this tyre would create a lot of problems - throw away some pieces of the tyre.

"So we chose the hard one and it wasn't good in the race. I wasn't comfortable, I wasn't fast. The only thing I could make was try and open some gap between me and Andrea. I've been lucky with Casey's crash."

Lorenzo soon lost touch with the race leading Repsol Hondas, but when joint championship leader Stoner fell at the penultimate turn Lorenzo was promoted to second and a 14-point lead over new nearest rival Dani Pedrosa.

Bridgestone confirmed they had advised some riders to go with the hard tyre.

"Sachsenring is a very abrasive circuit and after analysing the rear tyres after the warm-up session, we advised some riders to use the harder rear slick option instead of the softer rear to limit tyre wear during the race," said Shinji Aoki, manager of Bridgestone's Motorsport Tyre Development Department.

"Another benefit of using the harder rear slick is that its grip levels are very stable over the duration of the race as shown by Dani Pedrosa being able to set the fastest lap of the race on the very last lap."

Lorenzo refused to say if he felt the rear tyre advice had been a mistake, but reiterated that he was 'very slow'.

"We will never know... We chose this [tyre] because of the advice of Bridgestone. Not so bad finally. We finished the race. Very slow, but we finished the race!" he smiled.

Lorenzo also kept the pressure up on Yamaha.

"I'm optimistic that if Yamaha give me some new pieces in the future, to finish the championship with a little different bike, I can be much more competitive than at this race," he said.

Gresini Honda's Alvaro Bautista and Cardion AB Ducati stand-in Franco Battaini were the only manufacturer riders to use the softer rear.

Bautista rode from last to seventh and, although suffering with rear sliding, set his fastest lap on lap 24 of 30.

Lorenzo's best lap was less than 0.2s quicker than Bautista (0.753s from Pedrosa) and set on lap 10.