max Tire size for 66 convertible

[Geoffrey Yoder]

What are the largest tire size I can put on my 66 convertible? I am going to put on radials for the raod. Thanks

[Grant M.]

Re: max Tire size for 66 convertible

While I believe that 205-75/15 has been quoted previously on this Board as the closest size in relation to the original 7.75-15 tires installed at the factory, I installed 215-70/15 radials on my 65 convertible. Using original size 5.5" x 15" steel wheels, these tires have been fine, except for very slight rubbing on the frame at full deflection.

grant

[Duke W.]

Re: max Tire size for 66 convertible

The closest modern radial to the original 7.75-15s in terms or revs per mile is the 215/70R-15. The 5.5" OE wheels are at the bottom of the acceptable wheel width range for this size. You can also mount this size on a repro '67 6" rally wheel and install the OE wheel covers. Fender clearance may be tight, but should be okay. You can gain fender clearance by moving camber in the negative direction.

At full steering lock the tire shoulder might rub on the frame.

There is one Z-rated and one V-rated 215/70R-15 still on the market.

Duke

[Jerry G.]

Re:1 1/2 degree camber in rear does it *NM*

[frank mccracken]

Re:1 1/2 degree camber in rear does it

What is the max neg camber I can get away with??

[Jerry G.]

Re:depends

In my case I went with Dukes recomendation on tires and put on Pirelli 215/70s Z rated. Each tire has slightly different cross section thickness and profile. The problem I was trying to solve with camber change was to minimize risk of rubbing in the rear. In my case my body seems to be a little shifted on the frame and there was more clearance on the drivers side than the passnger side. I experimented with different camber settings and found that 1 1/2 gave me about a 1/4 inch clearance under all travel conditions for the rear. two degrees gets pretty noticible, it looks funny. I tried to have the same camber on both sides for handling characteristics. I am concerned that this much camber will cause a wear problem for me , but , it's better that crunched glass. I wanted to keep my original lips intact. If I had been willing to shave the lip I think I could have gotten away with factory setting of 0 degrees. But it depends on how your body is setting on the frame. Jerry

[Duke W.]

Re:depends

As a rule, negative camber settings will improve handling. For street driven cars negative one degree will usually not cause excess inside tire wear, particularly if you engage is a lot of "sporty driving" i.e. hard cornering.

The nominal front camber setting for C2s is fractionally positive and fractionally negative at the rear (specs vary slightly for different years).

For the front I recommend zero to negative one and negative one-half to negative one-and-one-half at the rear, with the larger negative settings considered as "performance settings".

A change in camber of one degree in the negative direction will improve tire to fender lip clearance by about one-quarter inch. For example if rear camber is negative one-half and the tires occasionally brush the fender lips, increasing the rear camber to negative one-and-one-half should provide about a quarter inch clearance.

Duke

[Timothy B.]

Re:depends

Duke and all,

How much larger and in which dimension would the 215/70-15's be as compared to the 205/75-15's that I currently have installed? In the rear, I currently have no problem with lip clearance and I would say there is probably 3/4" clearance or more. In the front, lots of lip clearance, but it seems both tires stop right at the frame on full lock turns.

[Duke W.]

Re:depends

215/70s are nomially 10 mm wider than 205/75s in max cross section and about one-half inch shorter. Go to The Tire Rack or manufacturer's web sites if you want dimensions for specfic make/model tires.

Clearance is also a function of wheel offset, so if you install wheels with different offset the equation changes. Overall cross section width varies with with wheel width, too. Tire max cross section increases/decreases about 40 percent of wheel width variation from the measuring wheel width.

Duke

[frank mccracken]

Re:depends

1 1/2deg neg camber it is then. Thanks Duke. Gonna come all the way down there and buy you lunch someday.

[frank mccracken]

Re:depends

I should also mention thanks to you Jerry Gollnick for your reply and advise.
:-}