1968 Help with 15" tire size

[68P51]

I could use some help deciding what size tires to get. I am running some new 15x7 Shelby 10 spokes and have never had the car running with these wheels. I just bought some BFG White Letter 205/60/15s but they don't look right to me (sidewalls are too small). It has Granada front brakes and doesn't have any rubbing with the very little (maybe 5 miles) it was driven with these tires. I found out the place I purchased them from will still exchange them. I've read a few threads on here and found out the stock tire diameter is 26.24" and these are 24.7".

I am trying to get the car to look as stock as possible, but have some other competing goals at the same time. The car does not have power steering so I want to keep the fronts narrow to ease the slow speed turning burden
in parking lots, etc. At the same time the new engine has quite a bit of power so I want to be able to use as much of it as I can and need something fairly wide on the back. I don't want it to look like a tubbed out dragster with
bicycle tires up front though.


Here's what I was thinking.

Front:
215/70/15 26.9" diameter 6.5" tread width
Back
255/60/15 27.1" diameter 8.5" tread width

or

Front
215/65/15 26" diameter 7.1" tread width
Back
245/60/15 26.6" diameter 8.3" tread width

Will this look ridiculous?

 

[Ruppstang]

Be carful how wide you go in the back or you may have rub issues when you hit a bump or have a load.

 

[franklinair]

215/70/15 FRONT & REAR.

Neil

 

[robert campbell]

The biggest variant in tire size is what height your car sits at. A lowered car will rub easier than a stock height car. Take a tape measure and measure from the floor up to the wheel lip and provide the dimensions front and rear.

The other factor is the backspacing of the wheel. I am not totally up on the Shelby ten spoke, but the Magnum 500 was a bit more "deep dish" with more of an offset towards the fender lip than a stock steel wheel. This also inhibits the use of wider tires.

There has been lots of banter on the site about tire size, but all of the above factors play in the decision.

Rob

 

[Mosesatm]

The stock tire size depends on which tires were originally on the car.
Here are some rough diameters.
6.95-14 = 25.0"
E70-14 = 25.7"
F70-14 = 26.4"

 

[68P51]

Thanks everyone. The car is stock height or maybe just slightly higher in the back. I'm going to go with these. If they rub I'll try the 245's. I would have gone with them but the diameter is smaller than the fronts and I thought that would look weird.

Front:
215/70/15 26.9" diameter 6.5" tread width
Back
255/60/15 27.1" diameter 8.5" tread width

 

[Mosesatm]

If your car has wheel opening moldings they may extend beyond the opening lip, requiring trimming them a little.

 

[robert campbell]

Arlie is right on as usual. My gut says you will be right on the edge with this tire combination. I hope your tire place will let you try them in the parking lot with 4 people in the car. Lock to lock in the front and even a short drive to go around a corner with some speed with the body shifting due to the corner. Lots of times you are just fine in a straight line but a corner will shift the rear end and cause a rub.

In my world things that spoil the pleasure of driving our toys is an exhaust leak, or TIRE RUBBING! It totally ruins your drive! Squeaks and clunks are right up there also! Another favorite is the clicking and pulsating speedometer!

Rob

 

[CougarCJ]

To add to what Rob said. Also lock to lock in reverse, slowly. Don't want to wipe out wheel lip mouldings or fender lips.

 

[robert campbell]

To add to what Rob said. Also lock to lock in reverse, slowly. Don't want to wipe out wheel lip mouldings or fender lips.

Scott,
Good call! I might suggest that you have someone watch the front tires as you move very SLOWLY!!

Rob

 

[Mosesatm]

You may get 255s to work but the wheels will need the perfect offset.

I ran 235-60-15s with 10-spokes on the rear of one of my cars and they scraped on the wheel opening trim going over what I call bridge bumps; when the bridge is higher than the rest of the road and the entire car goes whump on the other side.

 

[robert campbell]

You may get 255s to work but the wheels will need the perfect offset.

I ran 235-60-15s with 10-spokes on the rear of one of my cars and they scraped on the wheel opening trim going over what I call bridge bumps; when the bridge is higher than the rest of the road and the entire car goes whump on the other side.

Arlie, right on track again. I managed a set of 275 50R 15's on my GNS. They were 26 inches tall. They were on special ordered offset Cragers with a bunch of negative back spacing. They were darn close and the GNS was lowered.

You may consider a 70 series tire in the back that is taller but narrower than the 60's you are looking at. They will fill up the wheel opening and reduce the chance of rubbing.

Rob

 

[franklinair]

Found this on Facebook.

Neil

 

[robert campbell]

Dad,
That is very cool and from my experience seems to be pretty darn accurate.

Rob

 

[gazrox]

The 255's will not fit on the rear - they will rub (been there - done that!) I tried 235's on the front - same thing. I eventually settled on 215/65/15 - seemed to be the best combination for look and feel.

 

[1968Cally]

I want to get the Shelby 10 spokes for my GTCS. I want to get a 70 series tire but in radial. 215/70/15. Maybe 225/70/15

Car is stock height. Does anyone see a problem with either of these? The diameter would be 26.9.

Thanks.

 

[franklinair]

That's exactly what I put on a CS several years ago. Perfect fit, no problems.

Neil

 

[franklinair]

Just be sure the lug nuts a properly torqued...

Neil

 

[1968Cally]

Just be sure the lug nuts a properly torqued...

Neil

Thanks, Neil. What should the torque be?

 

[robert campbell]

I torque to 80 foot pounds.

Rob