Widest tire size to put on base 18" rims with spacers ? What size?
 

Just wondering if any of you guys are running very wide tire on base 18" rims with lowering springs and wheel spacers. I plan on buying wide spacers for wide tires on both my front and rear tires, ps: should I plan keeping a squar-ish set up or staggered for drifting most.

Also best fitment without rubbing, (I have Megan lowering springs I believe it's 1.2in in front and 1.0in in the rear)

The widest tires you can fit are 275/40 on the rear and 245/45 on the front.I currently have these on my car with a 5mm spacer on the back and 20mm spacer on the front with stock springs.I like the way it gives the car a little more aggressive look.When lowered I believe you can go a little more with the spacers.

exact same on mine.

Is that really the widest that can fit on the stock 18's, or is that just what people have done because it's more cost effective (moving stock rears to front wheels then buying 275's for the rear).

I'm actually wondering if you can safely fit 255/45 and 285/40.

You could fit 305's on the rear rims if you really wanted to force them on there,but it would look silly.If you look at the rim width recommendations for the 275's,the manufactures require a MINIMUM width of 9" which is exactly what the base rims are.For the 245's up front an 8" wheel is the minimum width recommended by the tire manufacturer,and again that's what the base rims are.I find the sidewalls look good and don't bulge too much,but even 285's in the back might be pushing it.Just stick with 275/40's in the back,they are the proper height exactly,285's will be a little taller.Having said all that,there isn't much difference between 275's and 285's:)

The base wheels are 8's & 9's....the overall width (lip to lip) are 9 & 10".
section on a 275/40 is 10.9";almost 2"wider than the bead & 1" wider the the width.
A wider tire will fit the wheel,but will be pinched.
If you've ever mounted tires on wheels you will know.

Okay so i plan on going 18x9.5 +22 with 265/40/18 in the front and 18x10.5 +15 with 295/40/18 ? suggestions comments

Not sure the tire manufacturer; But those sizes are about 1" different diameter,,,may end up with the Christmas tree effect (dash lighting all up because abs can't compensate).
I've seen guy's get away with 0.5",0.6"difference......not sure what 0.9"-1.0" will do.
Other's may chime in on this one/as i have no personal experience (yet) with running 2 different height tires.
As far as fitment on the wheels....no problems.

What tire size do you recommend I run with those rim specs? Sorry I don't know much on wheel tire sizes, but I do want a meaty look to it

are you looking for all season tires or max summer tires?

Gonna be hard to go wide & stay close to stock diameter with 18's,,,that 10.5" wheel can support a 305/35/18,,,but not many choices/that's more of a drag-radial size.

265/40F & 295/35'sR are probably the best choices....and probably a 275/35F & 295/35R would fit-pending tire mfg.

all season, and why 35 and 35 why not 40 45 ?

You said you want wide,,,a 45F & 40 rear will work w/30mm less width on the front & if you can find the mfg. who makes them.(example 255/45/18 & 285/40/18) & if they are the same series/35,40,45.....a 20mm width differential will work & only will be 1/2" shorter in front.
it's just harder finding wider section width tires (285,295,305,315etc..) in a 40series all season.
Michelin A/S 3+ offer's a 255/45 & 285/40,,,but not sure if that's wide enough for you & they are 27" tall...you mentioned you were lowered.