Join Date: Jun 2002
Location: Auckland, Aotearoa, New Zealand
Experience at a variance to 42/48
I wouldn't call it a debate, I would simply say that the question comes up a lot. The almost universal consensus is 42/48 for Bridgestone Radials and I have seen nothing different for the 020 bias-ply tires.
With 103k miles done on a 2000 with BT-020 Radials (except of the first two sets which were Excedras and Dunlops), I did for a long time use 42/48 consistently, checking tire pressures daily on long rides with a good guage I carry. I ride a steady 10 over on freeways, and ride it hard when we start getting bends anywhere, 95% 1-up. With 42/48 I got 6,000 - 9,000 miles on a front (12,000 once from memory), feathering starting after 500 miles, the tire usually being replaced because the feathering had got so bad.
So I went back to 36/42 and....got 6,000 - 12,000 miles on a front, feathering starting after 500 miles, the tire usually being replaced because the feathering had got so bad. The only difference being that the feathering pattern is different when severely affected (I had a picture on a previous thread from CCR Jackson Hole a couple of years ago). So now what I do is use 42/48 if I am riding multidays on a freeway (e.g. I am riding across to SF in a week from Philly) just because it "seems" like that would give me better mileage, else I use 36/42 (most of the time) just because it "seems" like it would give me better grip which is what it is all about really.
Overall, from my direct experience, there is no significant difference between 36/42 and 42/48 with BT-020 Radials on a pre-2005 bike.
With the rake/trail having changed on the 05+ bikes this would, I imagine, produce a platform that would potentially be not the same viz tire wear characteristics so I can't be certain there, though I would say that the similar mileage that people are getting with these tires (and bias as well) on 42/48 05+ bikes would induce one to believe the story is the same there.
Located: Auckland, New Zealand...
but I left my biking heart along the Scenic Byways of America.....
"Come fill the cup that clears
Today of past regrets and future fears." ....Omar Khayyam