I recently bought a set of Vossen CV7 rims for my g37 coupe. I am planning to stay at the stock ride height for my car because I live in an area with terrible roads and highways everywhere I go; there is no point in lowering the car when I'd just scrape or bust my bumper everyday. What tires can I run without rubbing the inside of my fenders in the front and in the rears? Would there be issues if I hit bumps in the road because of the the rims poking out (as in the rim hitting the quarter panels and fenders)?
The wheel specs are:
fronts: 20x9 +20 offset
rears: 20x10.5 +25 offset

 

I don't know why these photos ended up sideways. Sorries in advance!

 

What tires are you planning to run w/ those? Under severe compression it's possible the actual edge of the wheel could make contact, more than likely at stock height it's just the tire that could rub depending on the tire width you select.

Fronts will be ok, but the back at in-spec camber you could have contact, even w/ a stretched tire under real deep compression.

 

I'm not too sure on what tire size I should run. I was planning a 265/35/20 in the back, but I'm not quite sure. Any recommendations on what I should run in the fronts and backs? A VERY mild stretch is okay, but I don't want to stretch it too much because it can compromise the tire.

 

Here's a 20x10.5 +25 running 275s, but this is a lowered G, so the slight camber increase will result in more fender clearance, a 265 should get you a similar fit at stock height. This G is running 10.5 +25 & 275s front & rear.

 

If I hit a bump, would the stock height save my fenders and quarter panels from being hit by the rim?

 

That's the million dollar question, I'm not sure where the OEM suspension travel (hitting the bump stops) occurs. Also wheels w/ that aggressive offset may be safe following the natural camber arc when compressed but it's too close for me to say w/ certainty

 

Sorry if I sound a little ignorant, but what do you mean by "natural camber arc?" I don't think I fully understand. Sorry in advance!

 

Because our cars employ unequal length control arms (the top arm is shorter than the bottom - mounting point to mounting point), the car naturally gains negative camber as you cycle the suspension.

At ride height, you may only have 0.5-1° of negative camber (top sticks in more than the bottom), but as you compress the suspension through its stroke, the amount of negative camber increases. At full compression, you're probably nearing 5-6° of camber if you're at factory alignment.

This is so that as the car turns and starts to load the suspension, it can better use the entire patch of tire side to side and distribute the force amongst the tire.

So the lower you go, the more camber you get. And that in turn forces the tire/wheel combo to tuck into the fender rather than hit it.

I think my brother's car is 19x10.5 +15 square with 245/35R19 tires (or +23, will confirm) on bags and factory alignment, and it tucks all the wheels when fully aired out.

 

Thanks for clearing that up. I get it now.
If that's your brother's wheel specs, then it sounds like my wheels should be just fine at stock height don't you think?

 

Confirming that they are 19x10.5 +15. And yes, I think the wheels will be okay, assuming the tire doesn't contact first. But they will poke A LOT at stock height.

 

Thanks for the visual Chaos, and helping w/ the suspension/camber function.

I hate to say for sure there won't be a problem when running those aggressive setups, so getting as much confirmation as possible is great info!

There is a lot of room to travel prior to any wheel-edge to fender contact at stock height, so OP has that in his favor too

 

I think your bigger problem is your choice of wheel diameter. Those shorter sidewalls won't help with your crappy roads.

 

I got these Vossens for a very good deal, so it is what it is. I get what I pay for, so the shorter sidewalls are on me.