18s and 20s tire sizes
 

I've looked through 10 pages on the google search here and all I really see is answers for the 67-72.

I am a 4x4 guy and am rebuilding a 2wd short right now so this is my 1st go round with tire sizes on the 73-87. I currently have 15x8 and 15x10 ralleys. I was originally thinking 235-70-15s and 255-70-15s but I have been seeing that 255-70s on a 10 don't look that great so I changed my mind to 245-60s and 275-60s.

I have a couple of buddies that are telling me to ditch the ralleys and go bigger. I'm liking the 18/20 combo. My question is........ are 245-45-18 and 295-40-20s going to fit ok on a 4.5/6 drop? 4.5" backspace in the front and 5" in the rear. Will a 5.5" backspacing work on the rear wheels?
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Re: 18s and 20s tire sizes
 

I just did a 4.5/6 drop and I have a 295/40-20 in my rear and 255/40-20 up front, essentially a 30.4" wheel and a 28" wheel. The rear tucked in just fine but the front is buzzing/rubbing the inner fender. Your proposed front is only 26.7" tall so I don't think you'll have any issue front or rear.

Re: 18s and 20s tire sizes
 

Do you know off hand what the backspacing is on your rear wheel?

Re: 18s and 20s tire sizes
 

This is an 18/20 combo w/more drop (closer to 6/8). It had:

18x8 w/5.25"bs 245/45-18's
20x10 w/5.0"bs 295/40-20's

If I were doing one like it again, I would only do 4.75-5.0"bs on the front.

Re: 18s and 20s tire sizes
 

Same truck, same drop w/15" truck Ralleys. It had:

15x6.5 van Ralleys w/factory bs 215/70-15's
15x8.0 truck Ralleys w/factory bs 255/70-15's

Re: 18s and 20s tire sizes
 

Front Wheel - 20" x 8" Backspace 4.5"
Rear Wheel - 20" x 9.5" Backspace 5.25"

Re: 18s and 20s tire sizes
 

Scoti, so with my 28" front and 4.5" BS, this is most likely my issue with rubbing? Did you do any other clearance mods to get the tire to fit? Or is it fitting nicely because it's only 26.7" tall? Thanks for your help!

Re: 18s and 20s tire sizes
 

My wheels were pulled in further to prevent contact w/the inner lip on the wheel arch. I tried 28" fronts & they constantly buzzed the top of the stock inner wells.

Same truck w/same drop.....

20x8.5's 5.25"bs 255/40-20's
20x10's 5.0"bs 295/40-20's

The only extra mods done were the front upper shock mount was raised to allow a stock length shock. The bump stops were trimmed @ first but it buzzed the tires @ the top of the wells too much so I put new bump stops in that were trimmed even less (maybe 1/2" and trimmed @ an angle).

Re: 18s and 20s tire sizes
 

255/55/18 front 18x8 (0 offset)
285/50/20 rear 20x10 (0 offset)

Re: 18s and 20s tire sizes
 

Well, I went with 255/50/20's on the front and squeezed 305/50/20's on the rear. . . not lowered yet, but I wasn't going down as far as you are talking about going.

Truck is under the knife right now, so until I get back together in the next couple of weeks or so, I won't have made a decision on leaving it alone or dropping it.

You can see the change here in my build thread:

http://67-72chevytrucks.com/vboard/s...8&postcount=87

Re: 18s and 20s tire sizes
 

Thanks for the replies guys!