ok i need some advice from someone who knows what there talking about. My vehicle is a 1985 mustang GT, and iam buying some new rims and tire this winter to liven it up this spring. my stock tire size is 225/60-15, which gives me a overall tire diameter of 25.63 inches and 8.86 inch width. i would like to upgrade my rims to a 18X9 inch, 4 lug, cobra R rim, found on this site- http://www.americanmuscle.com. The front tires i would like to mount onto these rims have are 245/35-18's which have a overall height of 24.75 inches and 9.65 inches wide. My rear tires i would like to mount are 285/30-18's and have a overall diameter of 24.73 inches and a width of 11.22 inches.

Now here is where my questions start, i do not think i will have clearence or rubbing issues with the tires in the front, but i do not think i will clear the quad shocks in the rear. Now i know i could buy upper and lower control arms and ditch the quads, but i really do not wish to do that. i need to know how big of a wheel spacer i will need to buy to clear my quad shocks, i want it just thick enough to be able to safely mount these tires. so what is recomended for me to do this?

P.S. i plan on using these tires if it makes a difference. http://www.tirerack.com/tires/tires.jsp?tireMake=BFGoodrich&tireModel=g-Force+T%2FA+KDW+2

Thank you for your time and thought on my tire dilema.

would i have mounting issues if i just went with 245/40-18 on the front for a tire diameter of 25.72 inches and width of 9.65 inches, and 275/35-18's on the rear with a tire diameter of 25.58 inches and width of 10.83 inches? this is compared to the stock 225/60-15's with a diameter of 25.63 inches and width of 8.86 inches.

I have heard that you can mount 275's on the rear of a fox and clear the quads, can anybody shed some light on this?