19x10 front and rear issues
 

I bought STR607. I got a deal on them. Only problem with them with is they are all 19x10 +20 offset. Should I be needing spacer in rear to make it look proper? I haven't installed them. What is the spacers size would I need. Also I bought some coilovers to put on the car. Also I have a question on tire figment on those wheels. Would 245 40 19 will fit on 19x10?

Will need big spacers in the rear. Tires will be stretched. Terrible look imo. These q's should've been asked beforehand during your research. I suggest cutting your losses now and dump these crap wheels and save for better quality.

I'm planning on putting 245 40 19 on front and rear 275 35 19

That good deal wasn't a good deal after all. Those offsets are a mess.

Front tires will be more stretched than rears. Giving an uneven look. Not good.

If you're gonna stagger tire's on the same diameter wheel-A 1 width differential would look more uniform than a 3.
example: 265/35,275/35's or 275/35,285/35's...slight rake & with more weight up front, it would give a more even squish/footprint.
Also plan on a 25mm spacer on rear (20-30mm) depending on your camber setting's.

Thank you

Those I'd be tempted to run 285 square. At most 275f and 285r. And yeah as mentioned you'll need a good 15-20mm spacer for the rear to even things out.

A 285 square set-up with spacers in the rear would be your best bet.

For a reference my fronts are 19x9.5+15 which is basically 19x10+20 (+21) to be exact so 1mm diff.

I have a 245 40 19 on mine. It's a mild stretch. The stretch on a 10 won't be horrible BUT your rear with that will look horrific. My rear is a. 11 inch with +8 so that's like 25mm or more difference,

All numbers done in my head so I may be off by a mm.

Sell the rears. Buy a better size