Hello,

I bought the BFGoodrich Radial TAs on my 1972 442 in 1987, so even though they have some tread left on them, I think that I should replace them. I have 225/70/14 size on now, but was wondering if anyone was running 235/60/14 or 245/60/14. First need to know they fit without any modifications or rubbing. Second need to know how the look with a slightly smaller diameter/profile. Third is the tire width that I would be gaining work changing the profile apperance. And if anybody has any pictures of this size tire/wheel combo on a 70-72 Cutlass, I would love to see them. I have no interest in changing the wheel size to 15 inch.

Thanks
KMP
72 442 Convertible
11 Genesis 4.6
11 Venza

???

 

IMO run the 225/70/14s - the 60 series 14" tires look too "short" on a Cutlass/442.

 

Here's a shot of my car with 245-60-14 BFG Radial T/As on factory 14x7 wheels.
I should point out that I installed 442 FE2 equivalent springs which sit about 1" lower than regular Cutlass springs, so the tires fill the wheel openings fairly well. Since you have a 442 you should already have similar springs on your car.

P2250124.jpg

 

x2.

 

The 245/60s are a full inch smaller in diameter than the 225/70s. The 235/60s are even smaller than that. I do think that the look too small, especially on the rear. There's a lot of daylight between the rubber and the wheel opening in the photo above.

 

The flip side is that 225-70s are way too skinny when viewed from the rear. 245s still leave a lot of fender well space, but it looks a lot better.

Wider tire/shorter sidewall helps handling.
The shorter tire also reduces the effective gear ratio, providing a slightly "lower gear" for enhanced performance without swapping the rear.

 

The difference between the "way too skinny" 225s and the 245s is 8.9" vs 9.6" - about 3/4"

How they look is a matter of personal preference.

All else being equal, yes.

The difference in diameter between the 225/70-14s and the 245/60-14s results in a 3.8% difference in effective final drive ratio. I doubt you'd see a difference at the drag strip.

 

At this juncture I spring for 15 inch wheels and get a better tire selection.

 

I have never measured 225-70-14s but my 245-60-14 s are 23.5" tall, which is about 1" shorter than the BFG data shows. This would affect the overall gear ratio difference.

The skinny 225-70s going up in smoke off the line would prolly make a bigger difference than the tire height. Been there, done that.

Agreed.

 

You bring up a valid point, in that published or calculated diameter data is the theoretical unloaded diameter. Tires deflect under load. The important number is the rolling radius. Manufacturers of heavy truck tires actually publish that number, but most car tire manufacturers do not. Some publish the revs per mile, which SHOULD be based on the rolling radius and not the theoretical radius, but they don't specify. Of course, the rolling radius is COMPLETELY dependent on the inflation pressure, and the reality is that the taller sidewalls of the 225/70 tires will deflect MORE than those of the 245/60 tires at the same pressure, so the rolling radius difference between the two will actually be LESS than the difference based on a theoretical number.

I've never found BFG T/As to be particularly good drag tires in ANY size (and again, I'm talking the basic Radial T/As, not Drag Radials or other brands of T/As). The compound is too hard. The 3/4" difference in section width is unlikely to make a measurable difference in quarter mile times since both sizes will go up in smoke. I actually did run 245/60-14s on my 1972 442 for a while (tired 350 motor, four speed, 3.42 posi) and had no problems at all breaking those tires loose at will. If you have scientific back-to-back comparative run data that proves otherwise (not anecdotal butt-dyno "data"), I'd love to hear it.

Of course, not everyone cares about drag racing. The O.P. should collect all the data and make an informed decision based on his own driving and appearance preferences.

 

I was just trying to give the guy what he asked for.

 

I currently use 245 60 14 BFG Radial TA installed on SS II rims. They look just fine and perform well on both the 70 Cutlass Supreme and the 70 Cutlass Supreme SX. Two sets of five on two cars and I have not looked back.

 

When I purchased the 71 it had 245/60/14


4four2 002.jpg

 

A lot of good information here, thank you. I value everyone's opinion on this subject. My drag racing days are over. But back in 89 or 90 I ran this car on the same 225/70/14's that are still on it at the Super Car Showdown (anybody remember those?) and ran 13.90's. Now I just want her to look good and handle well on the street and for cruises and shows. But I do still like to get on it and chirp second gear.