I have this same brand in 17 inch tyres on my 525 and they are fine. Just to be sure I would start with the wheel nuts and make sure they are tight, stranger things have happened! I have been in a car that had a tyre change and the front wheel fell off, luckily at low speed. In my experience, sometimes wheels are more difficult to balance with just 'stick-on' weights, so they have to resort to clip on ones on the outer edge to get enough weight to compensate, although not all wheels accept them and they look unsightly too. I agree, it's a good price, I was expecting to pay £178 per tyre when I last checked prices in September, although wheel size will have a big impact on prices.