Tire/Rim Size Dilemma - 67 Cougar

Ok, I finally picked up the following rim sizes:

Rear: Rev Classic 105 - 15 x 8 / 5 x 4.5 4" BS Black - with BF Goodrich P255/60R15 T/A Radials

Front: Rev Classic 105 - 15 x 7 / 5 x 4.5 4.5" BS Balck - with BF Goodrich P205/60R15 T/A Radials


I took measurements when vehicle had no passengers or weight in trunk. With vehicle fully loaded the rear driver side rubs tire. The rear driver side sagged about 1" lower than rear passenger side any way so I decided to add new (1" higher than stock) rear leaf spring kit hoping this would solve my driver side sag and tire rubbing. This helped some but still rubs and driver side still sags slightly. Can anyone recommend what they would do to resolve problem with as little modification from stock as possible? I have been throwing around idea of air shocks but feel that this is only a temporary fix. The rear passenger side seems to ride ok fully loaded could it be just as simple as rear driver side shock being weak and possibly replacing with stock shocks or coil overs? Another thought was some type of rubber bushing that would bottom out preventing fender to rub tire.

Any suggestions would be greatly appreciated. I know getting smaller circumferance rear tires would be another option but like the idea of having extra support and mild lift anyway.

Oh one more thought, any idea of where to go on this site to post my vin/body codes? I checked out the Master Registry Forum but didn’t know if there was an official on-line data entry form somewhere.

Thanks for reading and your input.

The only option I can think of is stiffer shocks and maybe a longer shackle. Ninja edit, Is the tyre hitting the top of the wheel well or rubbing on the arches??

To fix it right you need more back spacing on the rear tire. 225 isn’t that wide, so I would think another 1/2" would do.

Just to put it in perspective, when I purchased my 67 XR7 I took it to get tested. When they tested the suspension I had 51% travel in my front right shock and 82% travel in the left. There was no way of telling just by looking at the car or even bouncing each corner manually. So you might have the same issue on your rear suspension only not visible to the naked eye. Just a thought bud.

He said he runs 255 rear bud.

OH…I swapped some numbers on that one…lol Yeah 255 is wide, measure how much clearance you got from the inside of the tire to the leaf spring and see if you have any more room for more back spacing.

You need 4.5" preferably 4.75" BS for a 8" rim on the rear. The 4" BS is your problem.

Sorry for the delay in getting back to your generous advice. The driver side tire is rubbing on the arches about an inch past the top tread line on the outer wall of tire. Since I would like a little more lift I would most likely pass on the back spacing and attempt to perk up the ass end with better shocks or air shocks? I’m afraid the longer shackle idea would look too much like a modification of the stock suspension if that makes any sense at all. If I went with air shocks does anyone know if there is a way I can charge shocks from under vehicle without penetrating underbody for access through trunk…etc. Again, the whole idea is not to mess with the originality/stock of car.

Please read my response and comment at will. Your advice is much appreciated!!!

Many people do it but it doesn’t make it right. Air shocks are a bandaid for the BS problem and put undue (and not designed for) stress on the unibody shock crossmember. Did it back in the day and eventually the crossmember spot welds all broke and I had a loose crossmember to deal with.

Holy crap…good to know…looks like air shocks are out of the picture. How about a combination of BS to 4.75" on the driver side only and stiffer newer shocks (no air shocks)?

That’s one sick looking Cougar you got!

Backspacing is a specification of the rims, you know that, right? It is the distance from the axle flange mating surface to the inside edge of the rim. You can decrease BS with spacers but you cannot increase it without changing rims. Now, it would be quite silly to change the drivers side (rear I assume) rim without changing the passenger side, don’t you think?

On my car, I run a 17 x 9 rear rim and have 5.25" back spacing. The wheel is nearly perfectly centered in the well. This is where I got the 4.75" suggestion for you on a 8" rim: 1" less wide, keeping the wheel centered in the wheel well means 1/2" off my 9" wheel’s BS, therefore 4.75".

About shocks, keep in mind that they have no effect on ride height (unless they are air shocks, we discussed them a bit), just dampening of the spring motion. So depending on what sort of ride and/or use you plan for the car, choose shocks accordingly. I like and use KYB GR-2 shocks. Think their designation may have changed but they are still sold.

Thanks for the comment re: Isabel. Still having a great deal of fun in my third summer after finishing her. Just finished a TKO-600 (five speed) trans upgrade. Love it.



Just checked, GR-2’s are now called Excel-G, 343146 front and 343219 rear. Cheap! at justsuspension.com, that’s where I got mine. Nice ride. Gas-A-Just are harsher, stiffer ride if that is what you are after. Cost some more too.

rock auto

$19.50 & $17.72

Sorry Bob :doh:

Hey, no harm no foul Bill! Cheaper is better!!!

then I MUST be the best!!! LOL!!!

At what …

That’s the .02 cent question!

Okay Muhammad… :buck:


Well a wheel guy in California that specializes in rims says you can just shave the bs of the rim at a machine shop to achieve the 4.75" BS. What’s your thoughts on this?

You’ll need to consult with a machinist, but If the online pics are accurate, there doesn’t appear to be enough material to work with.

Maybe this has been considered already: roll the inner fender lips.