Volume III, Issue 8, Page 16

How to fit fat tires on your G-body

GM’s G-bodies (’78 and later Malibu, Monte Carlo, and El Camino) are popular cars on main street as well as fly down the straight and narrow.  G-Bodies are the last of the mid-size rear-wheel drive platforms. They have a full (albeit a bit flimsy) frame, a relatively spacious engine compartment, there’s a ton of aftermarket support for them, and they’re easy to work on. 

Bliss? Maybe not. The trouble is the hind end where there’s limited room for big, sticky tires.  Typically, the most street tire these things accommodate is in the range of a P275/60R15.  And if you run slicks, a 9.00x28.00 is the largest you can get away with (and that might be a stretch). Even with these two tires, you’re usually forced to jack the back end up to gain the necessary clearance because the leading and trailing edges of the frame rail (closest to the back of the door jamb and closest to the bumper) are very tight to the tire, even though there’s plenty of room in the wheel well. Then there’s the catch with jacking up the back of the car.  If you raise it, you mess with the geometry of the back suspension. The factory 4-link instant center location is changed and typically, the car becomes a handful to hook.

Notching the frame sounds simple enough, but if it isn’t done correctly, it can turn ugly. It must be carefully notched and reassembled (plated) with fresh material and reinforced (with a crossmember) so that it doesn’t droop or bend following the surgery.  Once that’s complete, your G-Body will be able to swallow tires up to P325/50R15’s or 11.5X28.00-inch slicks, using the stock inner wheel well (tub).  Best of all, it can be accomplished at stock (or close to stock) ride height, thus preserving the suspension geometry.  We’ll show you how Lejeune Performance helped the frame in this writer’s G-body (don’t lynch me because it’s a Buick Regal). I have a home-built 572-inch rat going into it).  FYI, what works on  the Buford will work equally well on your ‘Bu, Elky or Monte.

A worm’s eye view of the typical G-body back end. The tires are P235/60R15s wrapped around stock wheels (barely 26 inches tall). It looks as if there’s plenty of room, but there isn’t, particularly when tire diameter is increased.  In the second photo, you get a better idea of the restriction. See where the frame swoops around the tire?  That’s one spot where it fouls tall, wide tires.