The Ford Barn - View Single Post - changing to 5.50 Bias Ply = changing to 3.54 ratio

M2M · 07-19-2019, 02:16 PM

I recently went from factory spec 225/60-17 to 235/65-17 on my modern car. Before the change my speedo showed 1-2mph MORE than the GPS. After fitting the larger diameter tyres my speedo showed 2-3mph LESS than the GPS. So don't let anyone tell you changing to a larger diameter tyre has no real world effect.

I was lucky enough to buy two new 550x19 BF Goodrich Silvertown Bias Ply for $130 each, they are normally $204 each.

The great thing about these BF Goodrich is they do not look like a "hot-rod" addition. Though beefier looking than the Goodyear they look at home on the Model A, especially on a Fordor, Tudor or pickup. The Russian GAZ-A got them and I've been told so did the Ford A 1931 Woody Station Wagons.

The Nokia 550x19 are cheaper because they are made in Viet (not USA) and are nylon not poly. They are probably a good tyre but I've heard of no reviews yet.

Apart from the BF Goodrich there's another 19" option. The beefcake Firestone 550/600-19 Bias Ply USA made 32" diameter 6-ply poly at $230 each. Apart from making a Mitchell o/d obsolete (just kidding!), if you plan to haul a few dozen cement bags in the back of your pickup you need these for their load capacity

My Tudor has a 3.78 I believe and I do not want an overdrive and I do not want to add a 3.54 or 3.27 unless my rear end needs a rebuild. Apart from that a bit more rubber on the ground for road holding and braking isn't a bad thing.

07-19-2019, 02:16 PM	#13
M2M Senior Member Join Date: Jul 2012 Location: Australia/USA/EU/Soviet Russia Posts: 1,105	Re: changing to 5.50 Bias Ply = changing to 3.54 ratio I recently went from factory spec 225/60-17 to 235/65-17 on my modern car. Before the change my speedo showed 1-2mph MORE than the GPS. After fitting the larger diameter tyres my speedo showed 2-3mph LESS than the GPS. So don't let anyone tell you changing to a larger diameter tyre has no real world effect. I was lucky enough to buy two new 550x19 BF Goodrich Silvertown Bias Ply for $130 each, they are normally $204 each. The great thing about these BF Goodrich is they do not look like a "hot-rod" addition. Though beefier looking than the Goodyear they look at home on the Model A, especially on a Fordor, Tudor or pickup. The Russian GAZ-A got them and I've been told so did the Ford A 1931 Woody Station Wagons. The Nokia 550x19 are cheaper because they are made in Viet (not USA) and are nylon not poly. They are probably a good tyre but I've heard of no reviews yet. Apart from the BF Goodrich there's another 19" option. The beefcake Firestone 550/600-19 Bias Ply USA made 32" diameter 6-ply poly at $230 each. Apart from making a Mitchell o/d obsolete (just kidding!), if you plan to haul a few dozen cement bags in the back of your pickup you need these for their load capacity My Tudor has a 3.78 I believe and I do not want an overdrive and I do not want to add a 3.54 or 3.27 unless my rear end needs a rebuild. Apart from that a bit more rubber on the ground for road holding and braking isn't a bad thing. __________________