I use a 1/2" Snap-on Tech Wrench for wheels and other big stuff. I have a 1/4" one as well. Digital torque wrenches are very nice to use, super accurate. It's a pretty expensive option though, even second hand on eBay. For my 3/8" torque wrench, I step up to the Snap on TechAngle wrenches for the numerous one-time use bolts on BMWs. For setting up differentials, I use a Snap-on 1/4" Torq-O-Meter dial type with a telltale needle.

But the above suggestion of CDI is a very good one. Pretty sure they make many of the Snap-on torque wrenches, particularly the digital ones. Precision Instruments makes other torque wrenches for Snap-on, including the Torq-O-Meters. You can save a lot by buying directly from these manufactures as opposed to Snap-on, but you won't have a Snap-on ratchet mechanism...but you will still have a super accurate, high quality torque wrench. If you buy a used wrench that is unknown origin, pay the extra money and have it calibrated before you use it.

As far as the need for a high quality torque wrench for wheels, the wheel bolts that BMW uses are pretty robust. But I've owned cars like a G35 that had wheel studs made out of some sort of crappy alloy, that 20 ft lbs of extra torque could snap right off. I have personally driven home from a tire shop and found I had only two wheel studs left unbroken on one wheel. But wrong torque can be just as bad on a BMW. Too loose, and you could loose a wheel. Too tight, and you can warp the hub and/or rotor. If you can't find a tire shop that torques all wheels as a matter of course, then bring your own wrench with you and ask them to use it.

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2014 BMW 328i Xdrive
2011 BMW 335i M-Sport
2008 BMW X5 4.8i Sport
2000 BMW 528i 5sp