Anyone use 305-30-20s?

1986 Buick GX1

GX1 #001 [The One and Only]
More than likely it would depend on wheel width and backspacing. I'm not sure if the size #'s you're using are calculated or actual, it probably won't matter.
I've run 295/50-15's (11.6"x 26.6) on an 8" wheel, not sure of backspace although I suspect 3 1/2" as they stuck out a bit with stock height springs and no rolled fenders.
It seems that 285's are as wide as you can run on a car that's lowered w/o a frame notch and may or may not need the fenders rolled.
I've got 285/40-17's on a 9" wheel, 4 1/2" backspace, no fender roll on the rear at the moment.

To simulate the extra width you could place a strip of 3/8" plywood on the inside and outside of your current setup, swing it around and see if it hits anywhere.
You may need to roll the fenders or add a spacer if close to the frame, or both.
Make sure you post back and let us know your findings, including wheel width, backspacing and lowered or not, if so, how low.
Maybe add the info with some photos to the sticky: wheel/ tire picture thread, show them off thread if you haven't already.
 

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Thanks for your comments. Sorry I didn't provide more wheel information but I was hoping that someone reading the post had actually used this tire size so I could find out what they had to do in order to make them fit, and then go from there. I know I might have to make some mods to minimize or avoid contact. I'm already using 7/16" spacers on the rear, but that gives me plenty of room for the tires I'm using right now, the 285-30-20s. My never-cut/never-rolled inside fender/quarter lip does make occasional contact but I have the lip covered with plastic molding that protects the tire from any contact, damage, or scrape. My rear wheels are 10" wide with a 5.5" backspace. There's still good tread on my 285s, so probably won't need to buy new until late Spring.
 

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UPDATE: Turns out I had a flat on one of my rear tires, 285s, and it ruined the tire. I took the chance of buying the NITTO 11.5" wide 305 30 20s for my 5.5 backspace, 10" wide, 20" billet Boyd Coddington rims. I have the camaro LS1 disc brake setup, and I'm using 3/8" universal spacers, longer wheel studs, of course, and had to trim my inner fender lip & wheel house moulding about 1/4", and installed Airlift airbags, not to raise the body but just to stiffen up for less travel. Body sits about a half to three quarters of an inch above the tire and thanks to the airbags don't make contact. They just fit.
 

fast86gn

Texas Moderator
Staff member
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Looks like Boyd Coddington Timeless 5's?

I run them in 17's, first time I have seen them on another TR.
 

fast86gn

Texas Moderator
Staff member
Search Timeless 5's you'll find em. They have changed slightly over the years but still the Timeless Series. I use to have Timeless 6 on my Rainier in 18's

BuickRainier2.jpg
 

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Search Timeless 5's you'll find em. They have changed slightly over the years but still the Timeless Series. I use to have Timeless 6 on my Rainier in 18's

View attachment 295593

I was thinking more in terms as the same wheels I have with the smooth lip and straight spokes. I saw a few models that were very different from mine, with curved spokes and standard shape wheel rims. Even the lug centers were different.. About the only thing the same was the name. .:eek:
 

1986 Buick GX1

GX1 #001 [The One and Only]
UPDATE: Turns out I had a flat on one of my rear tires, 285s, and it ruined the tire. I took the chance of buying the NITTO 11.5" wide 305 30 20s for my 5.5 backspace, 10" wide, 20" billet Boyd Coddington rims. I have the camaro LS1 disc brake setup, and I'm using 3/8" universal spacers, longer wheel studs, of course, and had to trim my inner fender lip & wheel house moulding about 1/4", and installed Airlift airbags, not to raise the body but just to stiffen up for less travel. Body sits about a half to three quarters of an inch above the tire and thanks to the airbags don't make contact. They just fit.

Thank you very much for sharing your results, I'm glad it worked out for you.
 

fast86gn

Texas Moderator
Staff member
I was thinking more in terms as the same wheels I have with the smooth lip and straight spokes. I saw a few models that were very different from mine, with curved spokes and standard shape wheel rims. Even the lug centers were different.. About the only thing the same was the name. .:eek:

Besides age I think the size and the off set have something to do with it as well. Mine are 17X8 with a 41/2 BS. And my rims are approaching 15 yrs old. I love the look but maybe its time for new ones?
 

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Besides age I think the size and the off set have something to do with it as well. Mine are 17X8 with a 41/2 BS. And my rims are approaching 15 yrs old. I love the look but maybe its time for new ones?

I know the feeling. I had the same 17X8 KMC 5 spoke chrome Stealth wheels, 17X8 w/ 4.5 backspace on my GN for 12 years. I wanted to upgrade, but never saw any wheels I knew I would like or would fit right. I found these already on a GN that was for sale on ebay and liked them a lot. I sent a note to the owner just to find some info on the wheels and he said he was thinking of selling them. I wasn't looking to move to 20s but it was either purchase these that caught my eye, already right there on a GN, or to procrastinate. I'm glad I went forward. Here's the Stealths below ...
 

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JAMCAR223

Well-Known Member
Thanks for updating this thread. As stated above, glad it worked out. These are the next tires I will buy to replace my 275/30/20. I don't mind trimming, as my car is far from stock.
 

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Thanks for updating this thread. As stated above, glad it worked out. These are the next tires I will buy to replace my 275/30/20. I don't mind trimming, as my car is far from stock.

Well, be advised, they're very close, but I've put a few hundred miles on them, over some rough highway, and I'm quite pleased I took the chance on this size.

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With these huge 305s, on 10" rims, I think that if you ordered custom rims with a 5.25" backspace, they would just fit with no modifications. Mine have a 5.5" backspace, so I had to use approx. 3/8" spacers to avoid frame contact.
 

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