nizmugen

The wheels are 19x8.5 ET33 so I went with 245/35/19.

jadedj

19's

RacermeX

What's the largest tire sizes that can be installed safely without having to reconfigure the suspension or ecu?

I was riding on 245/40/18s which seemed a little rough, so I replaced the tires with 245/45/18. The car is a bit higher, but feels much more comfortable on the road. The wheel/tires seem to fill in the wheel well just fine with no rubbing.

The tire diameter is about 16.5" across, but top to bottom is ~16" with the weight of the 2007 e61 530xi wagon.

JayArras

You can go to 17 inch rims on an xi, which will give you the ability to go to a 55 in a tire. The most important aspect is to keep the rolling circumference the same on all four wheels. Going out of spec will affect your speedometer however.

RacermeX

Thank you JayArras!
Do you know what the spec range is?
I assume that I am now out of spec.

JayArras

Try using something like this:

https://tiresize.com/calculator/

https://www.willtheyfit.com/

sunny201

I don't believe there is necessarily a spec you have to stay between as long as the rolling diameter of all four wheels are the same, as JayArras mentioned. Only difference is that your speedometer will be slightly lower than your actual speed, which is shown via the calculation in the first link he posted. Also, your braking and acceleration might be a little weaker due to more force being needed

RacermeX

Thank you both!
I didn't mean to hijack the thread

norsecarnut

This is the best size IMO. I've been running 245/45-18 since about 2011 for both my winter Nokian hakka..R2 on factory sport 18x8 and also the summer/shoulder season set on M3 8.5x18 ET 29 . Both are square sets or course and I also always have a matching full size spare (even with the nokian being a RFT because rft are for safety of where you do the spare changing, not for driving for hours in my opinion). The "summer" set is really a high performance All-season but I switch to the true winter mid november or first trip to ski and remove it early so as to not wear it out on warm pavement in the spring.

When do you least want to deal with a flat tire? IMO in the dark when it's cold and or dark and raining or snowing on the side of a road. With the RFT, and a full size spare, you first don't have a catastrophic failure event in what is more likely to be shit road conditions, then you can also take your sweet time to get to a safe place to simply swap out a wheel. I say simply because frankly, otherwise it's the side of a dark highway with cars flying by and road spray and usually very uneven ground, or worse, plowed snow so there's literally no where to do a tire change. Simple is driving to where it's off the road, out of the weather maybe, where there's flat open ground. Then it's really just a 20 minute job if you have the right tools with you.

Jack
Socket
Wheel lock socket !!!!!
Breaker bar
Decent Air pump to be sure spare is up to par as well as basic standard car kit item. (like a $100+ Viair, not some shit plastic end Kobalt junk - trust me!)

Pro kit:
Ideally a ratcheting torque wrench as your installer.
Wider base for a jack in case of soft ground
Folding wheel chock for weird/uneven ground
Large heavy duty trash bag for incredibly dirty tire to go back in the car.
Warning triangle or similar at least reflective but there are nice LED versions too that blink and help you stay alive.

norsecarnut

Yes, I have m3 whee;s which are the fronts and spec: 8.5x18 ET 29. A 245/45-18 just ever so slightly rubs the front of front fender liner on one side but I can't remember of it's driver or passenger. The rub occurs right around maybe a 30% turn. This means that on the highway it can never touch and even doesn't seem to touch on most street turns but you'll definitely turn across that spot into a driveway - basically because the faster you're driving, the larger most normal turn radius will be. Unless of course you've making emergency maneuvers but how often does that occur?
Over several years and 100,000 miles, the fender liner still only has the marking of the rub, not a run through but this would also vary by tire shape and also suspension height. My car is at factory height. A lowered car would run into that spot more easily I'm pretty sure due to the camber and shape of fender liner.