1966 Coronet: Largest wheel/tire combo that'll fit?

Looking to fit the largest 15" wheel and tire combo out back on my '66 Coronet 440 2 door without mini tubbing. Trimming the 1/4 lip is acceptable. I currently have '78 Córdoba 15x7 wheels which I understand have a 4.25" BS. Tires are 245/60/15.

I've searched on the net high and low and found the following info:
-15x7 Cop wheels have a 4.5" BS and with 275/60/15 tires should fit. My question here, does it fit with low stock ride height?
-15x8 aftermarket wheels will fit with 275's if the BS is 5.5"
-Seen a couple of 15x7 American Racing Torq thrusts with 275/60's mounted. Confused as the BS is 3.75" on those wheels which would mean they would rub the quarter lip, correct?

Hoping for owners of these cars to chime-in and let me know their real world combo that actually fit.

I'm also considering installing Super Stock springs. Will I need C body shocks if I run those? I did on my '69 Bird.

Thanks in adavance!

Mine is a 67 Coronet 500.

Put a set of 255/60/15 tires on 8 x 15 4.5" BS rims. They would rub on turns on my molding that is a little wider than the lip. They probably would have been ok with 15x7 rims with 4" BS but I went conservative and went 4.25" BS. This moved the rim in 1/4' towards the leafs.

No way could I fit 275/60/15 tires in my car with that molding. Without the molding and trimmed lip - maybe. I know others have done it so you need to hear from those that actually did it.

I am currently working on this exact issue. I have a 67 RT with stock rear suspension. I put 15x8 4.5BS wheels on the rear with 275/60 tires. I don't have the trim moulding on the car so I trimmed the wheel lip to only leave approx 1/4" remaining. The do not rub on the lip at all. The only place they rub at the moment is up in the inner wheel tub on the outside edge. The back side of the tire doesnt rub at all. It doesnt rub during straight driving but always rubs during any sort of turning as the body has flex.

I really like the look of the 275 on the car so I may have to widen the wheel tubs some to give proper clearance.

I'll take some pictures tomorrow to show my setup.


p.s. my passenger side doesnt rub anywhere....it is only on the driver side. When I measure, my rear end is slightly off center which I am told is fairly common.

Thanks Mark! Appreciate the input. So it sounds like the 15x7 with 255's is safest bet with 4" BS. You think the Torq thrust with 3.75" BS will clear too? No trim moulding on 1/4.

Awesome info. So it sounds as though if the rear end is higher like with SS springs, the rubbing on the outer wheelhouse will be a non issue with some 1/4 lip trimming. The added bonus is the 15x8 wheels you are running! Great info and appreciate you sharing your insight. I know what you mean about one side closer to the 1/4 lip than the other. Very common for sure!

If you can post the pics, that'd be great. Curious to see what it looks like and how far your wheel is tucked vertically under the 1/4 skin

I do not - I believe you would need 4" BS. Remember 15x7 4"BS puts center of tire in the same spot as a 15x8 4.5"BS.

Best fit on mine was a 15x7 4"BS, with a 235 tire. I tried 4 wheel sizes and 255 just never worked. The tire rubs the inner fender well toward the outer quarter when turning as the axle rotates at the center section. Tried trimming the opening lip which helped, but not with the inner well. You can get a custom wheel made with custom offset, but the outer lip would be shallow.

Two pics attached of two slight varied sizes. Obviously I did not have to deal with the wheel opening lip, so I had 3/4" more clearance than someone with a restored car.

275/60x15 on a 15x8 with 4.25" backspace street tire on traditional Cragar SS. 28x9.50x15 on 15x8 with 4.5" backspace drag slick with a Cragar Dragstar.

I don't think you could use a wheel with more than 4.75" of backspace. The wheel well is narrower than the frame rail inside there. Too much backspace and you stuff the tire into the well.

The part that rubs above the fender lip can be pushed out with a bottle jack and a torch.

Thanks for the additional info and pics everyone! Good to know backspace is limited and using a bottle Jack can give me the additional clearance I'm probably going to need.
When I get this done, I'll post my findings. Thanks again

Back spacing will depend on the wheel width..

I spent many hours with a tape measure and metal measuring stick, trying many different types of wheels with different backspacing before I ordered the wheels for my 67 Coronet..

I used 15 X 8 with a 5 1/4" backspace and a 245/60 15 tire for the back wheels of my car...

If I changed anything, I would order ( on my 8" wheels) them with a 5 1/8" backspace....

A lot of people on here will tell you a 275 tire will fit.. If you cut out the lip and make it a "downhill" car ( rear end jacked up in the air) would be the only way, based on working with my car....

An item you need to be aware of on the tire is "section width". This is usually wider than "tread width".....

Someone else on this site made a comment that the housing is slightly offset on our cars.. Mine did require an 1/8" spacer on one side ( driverside I think)

A HUGE difference on my car was the installation of a firm feel rear sway bar preventing tire rubbing....

Hope this helps

I have a 275/60 15 drag radial on my 66 sedan with no trimming I have calvart springs 1 inch lower and cop car 15x7 wheels never rubs even with 4 people in the car can't get a pic to load

Told you.....

I can't emphasize the use of the torch enough. Without it you could do some damage to your quarter even though you don't think you will. Don't ask me how I know. Mine is minitubbed so I can't help you with tire size or backspacing

Rapom, that is a killer ride you have there! Love the look with the fatties out back, too bad I won't go as far mini-tub since this is an original Hemi car I'm doing this too.

Rapom, question... Are those 15" steels in front with the 14" centers that'll accept the correct larger hubcap?

275 60 15 on a 15x7 with about 4.25-4 3/8 BS. Fits fine, been doing it for years. SS springs on one car, 50 year old springs and shocks on the other. Both fine. Is a [censored] to get rears off though, I'll admit.

Thanks Jeff. I'm going to give the 275's a shot on the current 15x7 Córdoba wheels I have currently. I understand they have a 4.25" BS.

On my '67 Belvedere, a 255-60x15 on a 15x7" with 4.25" BS was the best fit without issues.
A 275 will go but for me was wasn't worth the occasional rubbing. Others have done it and say they have had no problems, I've done it and I'll just say I won't do it again. There's a reason is a 275 tire on a 7" wheel is not recommended, it should be on a 8".
If you do run a 275, let the air out to make for an easier squeeze into the wheelwell.

Buddy of mine has a 66 Satellite Hemi Auto that has I think 255-60-15 on 15x8 wheels ( don't know the backspacing ) Next time I see him I'll make sure but I dont think they were 275's

Stock rear suspension and no air shocks. With 2 adults and normal driving its fine.
They will rub if he throws the car into a curve hard ( really aggressive driving) or they will rub if he puts people in the back seat and hits the slightest bump.
90% of the time its just him and his wife. He's 63 so aggressive driving sprints is extremely rare

Thanks for the nice comment on my Coronet. It took a long time to get it to where it is.

The rim's up front are the newer style (68 and up 15x7's). I welded 1/2" short bolts, with the hex heads cut off, (3) spaced evenly around the part of the rim where the hubcap snaps on. The older style hubcaps are 1 inch wider than the newer caps so adding a 1/2" does the job.

The rear are the old style 15's that I had widened. You can find them on half ton Dodge pick ups from 1960 to 66 all Studebaker's in the early mid 60s and some c bodies from 66 or 67.

I have a pair of old style 15's that l didn't use for the front because they are too narrow.

Guessing the reason these "fit" is the 7" wheel, making the section width smaller????

Yes, a 7" squeezes them a bit. I run 30psi and have no issues. I put 4 people and groceries in the car and only very very slightly rub with the 50 year old springs. I mean slightly. The SS spring car I could put gravel in the trunk and it wouldn't rub.

Also 15x4 old studebaker rims fit the larger dog dish. I have a pair on front of mine. You have to look at the rims carefully for rust or cracks. I've always read rumors from old timers of these being prone to crack.

Thanks again Rapom for sharing your setup and findings!

Thanks again Jeff. I have a couple of 275's from another project and the 15x7's and SS springs so I'll definitely be trying this out.

Thanks everyone for the input!

Here's the thing with putting 275-60-15 tires on 15 x 7 inch rims...

Just because you can , doesn't make it right !!!

I know I will hear it , but that's my firm opinion !!!

Also as a side note , all factory 15 x 7 Cop style wheels ,
with the vent holes in them , are 4.25 backspace.

Also for that car 15 x 7 with a 255-60-15 tire fits best.
Yes one side maybe tighter that the other and you may need
to do some trim work to clearance everything....

Frank

Personally I don't calling " needing some trim work" as " fits best"....

Many thanks to everyone including Jeff.
I put the 275/60/15's on the Córdoba 15x7 steel wheels and they fit perfectly on both sides.
Here's some pics of the clearance. Haven't put the SS springs yet, but no rubbing yet with stock height springs.

Looks killer tucked in the stock wheel tubs.

Awesome!

Thanks moparpollack! Love these early B-bodies!

That looks great. It will probably rub a little bit on turns with inclines but I would put up with it for that look.👍

Thanks rapom. Agreed, worth a little rub I'll post updates if it rubs in the future.

You might be surprised how quickly it will "rub" through your sidewall..

He'll have to try it and see.

So I don't have any photos at this time, but should have some this weekend if the weather holds up. I have been slammed at work and also had an injury that slowed me down a bit. My 275's still rub on the drivers side (outside wall of tire) during an occasional left turn. I used a torch to clean off the undercoating so I could try to widen the inner wheel well some on the outside of the tire. I was very careful and used a bottle jack and a torch but every time I removed the bottle jack, the tub just moved right back into its original position. Anybody have any tips on using the bottle jack/torch to "open" up the inner wheel tubs? If you look in the trunk, there is approx 3" of clearance from the inner tub to the quarter panel. If I could get 3/4" more clearance then I could keep the 275's and not have to waste money buying 255's for a swap. Any thoughts?

so whats the backspacing on these wheels?
you have a pic of the front wheel/tire too, i'm going to order some new front wheels soon probably.

The b.s. on OEM 15x7" wheels is 4.25".

Here are a few pictures of my rear setup. As I said before, there is a slight rub on the drivers rear during an occasional left turn. I plan on massaging the inner fender tub on the side of the quarter panel to get some additional clearance. I really like the look of the 275's.

I have no clue why the photos are sideways. In the file on the computer, they appear correct.