Maximizing BFG Radial T/A Traction
While I'm deciding on whether to switch to a street radial and which one I decided to see how much more traction I can get out of my 275/60R15 BFG Radial T/A's on 8" wide Mopar Rallye wheels. Temp today here in SW Florida is 88 and blue skies. I tested at a giant parking lot that was 90% empty. Thank God most of the "snowbirds" and tourists left for home. I had at least 1/8 mile of clear driving with no cars anywhere near my lane.The parking lot is a sealed blacktop and I'm sure the surface was hot. The car is a 1972 Duster with a mild build 440, 727, 3.23 sure grip.
I started testing with 28 pounds of air in each tire. I had driven 3 miles to the parking lot so the tire temperature was normalized. I used a fat piece of sidewalk chalk and drew a 2" band across the back of each tire while the car was pointed absolutely straight. I jumped in the car and drove at about 25 to 30 miles an hour for the 1/8th mile and brought the car to a stop. I inspected the chalk mark that I had made and at 28 pounds the interior 3 tread bands were completely erased but the outer bands were mostly still covered. So I kept repeating that process while dropping tire pressure a pound each time. I could see the outer band getting less and less coverage each time but the change was slight. When I got down to 22 pounds I stopped testing with the chalk and did a short burnout. The attached pictures show the patch on the blacktop. You can see that all 5 treads of The BFG tire were making contact. I measured the width of the patch on the blacktop and I got 7.5". While the outer two tread bands did make some decent contact with the surface they were narrower than the actual tread on the tire. I'm not sure if that's because those outer treads on the inboard and outboard edges of the tire have a round shoulder probably for when the tire leans in turns.
BFG specs say that tire has a 9" tread width and I measure 9" of "flat" tire surface before the outer band radius kicks in. At 22 pounds I'm measuring 7.5" of tread width from the actual burnout patch.
Has anyone on here done some similar testing? What were your results?
How low of a tire pressure do you think is safe to daily drive this BFG tire? I stopped at 22 pounds because my one test burnout was rather loud and I wasn't looking to attract attention. I'm told that as I continue to drop the pressure I will start to reduce contact with the center of the tire tread. Anyone using a similar size tire to mine... what's the pressure you shoot for when the tire is up to temperature?
I'm planning another session this time starting at 22 pounds. Glad to have reduced it 6 pounds... so far.
While I'm deciding on whether to switch to a street radial and which one I decided to see how much more traction I can get out of my 275/60R15 BFG Radial T/A's on 8" wide Mopar Rallye wheels. Temp today here in SW Florida is 88 and blue skies. I tested at a giant parking lot that was 90% empty. Thank God most of the "snowbirds" and tourists left for home. I had at least 1/8 mile of clear driving with no cars anywhere near my lane.The parking lot is a sealed blacktop and I'm sure the surface was hot. The car is a 1972 Duster with a mild build 440, 727, 3.23 sure grip.
I started testing with 28 pounds of air in each tire. I had driven 3 miles to the parking lot so the tire temperature was normalized. I used a fat piece of sidewalk chalk and drew a 2" band across the back of each tire while the car was pointed absolutely straight. I jumped in the car and drove at about 25 to 30 miles an hour for the 1/8th mile and brought the car to a stop. I inspected the chalk mark that I had made and at 28 pounds the interior 3 tread bands were completely erased but the outer bands were mostly still covered. So I kept repeating that process while dropping tire pressure a pound each time. I could see the outer band getting less and less coverage each time but the change was slight. When I got down to 22 pounds I stopped testing with the chalk and did a short burnout. The attached pictures show the patch on the blacktop. You can see that all 5 treads of The BFG tire were making contact. I measured the width of the patch on the blacktop and I got 7.5". While the outer two tread bands did make some decent contact with the surface they were narrower than the actual tread on the tire. I'm not sure if that's because those outer treads on the inboard and outboard edges of the tire have a round shoulder probably for when the tire leans in turns.
BFG specs say that tire has a 9" tread width and I measure 9" of "flat" tire surface before the outer band radius kicks in. At 22 pounds I'm measuring 7.5" of tread width from the actual burnout patch.
Has anyone on here done some similar testing? What were your results?
How low of a tire pressure do you think is safe to daily drive this BFG tire? I stopped at 22 pounds because my one test burnout was rather loud and I wasn't looking to attract attention. I'm told that as I continue to drop the pressure I will start to reduce contact with the center of the tire tread. Anyone using a similar size tire to mine... what's the pressure you shoot for when the tire is up to temperature?
I'm planning another session this time starting at 22 pounds. Glad to have reduced it 6 pounds... so far.
