[imsleeping88]

The Colorado roads I have to suffer every day are absolutely ridiculous. Too many semis around here. I'm looking if I'm able to fit thicker tires like a 45 instead of the factory 40. Does anything else need to change besides just straight-up getting thicker tires?

[Dom147]

When staying within the same wheel diameter there's not much you can do since you're not supposed to go beyond a 3% difference in overall diameter. What you might be able to do is go to a 17" wheel and from there do 245/40 which should be a nice bit thicker compared to the 225/40.

Here is how a 17" wheel looks on our vehicles.
https://www.2addicts.com/forums/show....php?t=1393898

[marcthedark]

Originally Posted by Dom147

When staying within the same wheel diameter there's not much you can do since you're not supposed to go beyond a 3% difference in overall diameter. What you might be able to do is go to a 17" wheel and from there do 245/40 which should be a nice bit thicker compared to the 225/40.

Here is how a 17" wheel looks on our vehicles.
https://www.2addicts.com/forums/show....php?t=1393898

WHere is that number coming from? Usually the % refers to difference between front<>rear (and for BMW the rumored figure is 1%) ... or is that to keep the speedo correct?

[Dom147]

What you might be referring to may be to what people who have xdrive have to deal with. Im not too sure about that. However, what I'm referring to also is wheel speed issues with your ABS/DSC when going beyond 3%.

[SpencerC_6MT]

Originally Posted by imsleeping88

The Colorado roads I have to suffer every day are absolutely ridiculous. Too many semis around here. I'm looking if I'm able to fit thicker tires like a 45 instead of the factory 40. Does anything else need to change besides just straight-up getting thicker tires?

I'm on 245/40/18's, about 4% bigger than my factory rears and 3% bigger than fronts. The speedo reads a little high by design, so I actually aligned it just right with GPS, but now my odometer is reading 3.5% slow. Liveable, yet annoying. Since I'm assuming you're on factory 18x7.5's, the 225's fitted from factory are actually pushing the limit for that wheel width. Your best option without changing wheels and keeping diameter similar is 205/45/18 imo, the 225/45/18's are over 3% increase in diameter. Remember that the middle number isn't a constant, it's a function of tire width as well, which is why a 225/40/18f is paired with 245/*35*/18r on the factory staggered setup. https://www.willtheyfit.com/ will be an important tool in this decision.