I have a mazda6 v6 2009. It currently has 18inch rims, I was wondering how much bigger I can go without interferinf with the stering.

 

+1 as a general rule will definitely fit without a problem (depending on the offset) though +2 will often times still fit with few problems so long as you are mindful of the offset and tire size.

-Cameron Keffer

 

Thanks for the reply, but can you be a little more specific please.

 

It's a little hard to know exactly what will work and fit.
What we know is that the '03-'08 models had a +60mm offset and aftermarket rims don't usually come that deep so a +50mm will push the wheel out toward the fender about 1/4".
If going w/a wider wheel that can be a good thing for suspension clearance. Too much more offset and you will be hitting the fender and have to roll the lip(s.) Plus you are liable to LOSE any handling gain you hoped to achieve since the wheels centerline will be way out of spec. This can and will affect steering angle, tracking, ride and braking, in that order. You will experience greater bump steer and suspension component wear the further out you go.
Generally the 6 series does not have a lot of options in this department. It was built and designed as a family car. There are those that have highly modified versions of the 6, our own Mazmart Trini is one, but they are knowledgeable, have resources and shops with the correct tools to help them work through any additional changes/alterations that need to be made. And I'm sure even MT will tell you that there are compromises you will have to live with once done. Everything mechanical is a compromise.
Personally, I think you might be asking for trouble if you go bigger than a 19"... and why would you want to?
If you plan on lowering it, which would offer a greater handling improvement than bigger wheels, AND you plan bigger wheels, you will really some have problems to work out.

My biggest problem with the 6 series cars I drove (short of the auto-stick) was the lack of body roll control. If I were you and wanted my 6 to handle better, I wouldn't waste my money on wheels and tires until I got some HD sway bars and lowered the car some. That's where the biggest improvements in the handling and stability of it will come from.

 

I have an 04. Right now it has the stock 17's. I was thinking of getting the racing beat springs and lowering it only about .075 inches, and then either getting 18s with 225/40 tires or 19's with 225-235/35 tires. What would you suggest for the best overall look but also the best overall performance. I dont want to harm the vehicle in any way and only improve its handling.