It's hopeless to actually get him to lend his car, he sleeps with the keys next to his bed, and the keys never leave his side when he's awake. He's never lent a car to anyone but his closest mates that he knows has "acceptable" driving skills.
I did actually ride with him, that is how I knew he was'nt using winter tyres, and while he did'nt slide or skid (Impressive in a Volvo 745 with a few hundred hp, no ABS or anti-spin) I was on the edge the whole time.
Does your brother drive on old or unstudded tyres btw? Makes a helluva difference if there's any icelayer at all.
You can get a 1500kr(~180$] fine if you don't have them, and if there is a "winter road surface"; for instance, ice, snow, slush or frost on any nearby roads. It's up to the cops to determine, but when there's 20cm's of snow...