...what thickness of a spacer are you running with 245mm tires and 18" rims for a flush look? Do i need spacers in the back only or in the front too? thanks.

 

Depends on your offset. What's your offset?

 

definitely depends on your offset and width of those 18's u got

 

My rims are 18x8 with 38 offset. I'm running 245x40x18 tires. The rears are almost flush. If I added a spacer it would probably be only 5mm. Anything more would be too much, especially when I get my coilovers and drop it more. The front is flush, no spacers needed.

 

I've ran 18x8.5 w/ 37mm offset w/out any problems. Tires were 245/40/18s w/ S-Tech drop.

 

I was running 18x7.5 on 235/40 with a 15mm spacer in the rear (42mm offset) and it was really nice and flush. However it kept rubbing with passengers or heavy loads in the back.

I now have 18x7.5 on 245/40 with a 5mm spacer in the rear. No problems whatsoever, however not as good looking with the lack of 10mm

 

I'm running his old wheels with the same size tires with 8mm spacers in the back with no problems.