Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 07-19-2019, 01:15 AM   #1
M2M
Senior Member
 
M2M's Avatar
 
Join Date: Jul 2012
Location: Australia/USA/EU/Soviet Russia
Posts: 1,105
Thumbs up changing to 5.50 Bias Ply = changing to 3.54 ratio

475-19 Goodyear diamond tread. USA made in 4-ply poly.
Diameter= 28.82"

550-19 Bias Ply BF Goodrich Silvertown. USA made in 4-ply poly.
Diameter= 31.10"
(this size tyre was factory fitted to later production Soviet GAZ-A)

475-19 Goodyear
Motor RPM= 2000
Differential Ratio= 3.54
MPH= 48.5

550-19 Bias Ply BF Goodrich
Motor RPM= 2000
Differential Ratio= 3.78
MPH= 49

__________________

M2M is offline   Reply With Quote
Old 07-19-2019, 04:21 AM   #2
Bruce of MN
Senior Member
 
Bruce of MN's Avatar
 
Join Date: May 2010
Location: VA
Posts: 1,395
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Deleted
Bruce of MN is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 07-19-2019, 08:24 AM   #3
Railcarmover
BANNED
 
Join Date: Apr 2017
Location: Sacramento
Posts: 1,262
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Hotrod overdrive,its why big rear tires were put on them..today its about 'stance',back then it was about road speed.
Railcarmover is offline   Reply With Quote
Old 07-19-2019, 09:15 AM   #4
jhowes
Senior Member
 
Join Date: Jul 2010
Location: upstate NY near Mass border
Posts: 789
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Now what speed do you get with the 550 tires and the 3.54 rear?
Jack
jhowes is offline   Reply With Quote
Old 07-19-2019, 09:31 AM   #5
mike657894
Senior Member
 
mike657894's Avatar
 
Join Date: Oct 2015
Location: Bay City Michigan
Posts: 1,050
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Is there a brand I can get them in cheap? around $100. or what do they cost? The speed is probably worth it.
mike657894 is offline   Reply With Quote
Old 07-19-2019, 09:53 AM   #6
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Posts: 2,332
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Sponsored Links (Register now to hide all advertisements)
M2M

I am running 7 X 16 Tornel bias ply with a 3.54, circumference 30.8 inches.

I have checked speed at multiple side of the road radar displays and am dead on. Went with these because they give me the same results as standard OEM rims/tires.

Picture shows tires, spare is standard rim/tire.

If interested I will go for run and see what speed is 2000 rpm. Let me know if interested and I will post back.
Attached Images
File Type: jpg loaded.jpg (84.7 KB, 51 views)

Last edited by 30 Closed Cab PU; 07-19-2019 at 09:54 AM. Reason: typos
30 Closed Cab PU is offline   Reply With Quote
Old 07-19-2019, 10:39 AM   #7
Y-Blockhead
Senior Member
 
Y-Blockhead's Avatar
 
Join Date: Jul 2011
Location: Redondo Beach, CA
Posts: 5,817
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by jhowes View Post
Now what speed do you get with the 550 tires and the 3.54 rear?
Jack
52.2 mph

Last edited by Y-Blockhead; 07-19-2019 at 11:04 AM.
Y-Blockhead is offline   Reply With Quote
Old 07-19-2019, 10:47 AM   #8
wmws
BANNED
 
Join Date: Feb 2013
Location: Coatesville, Pa
Posts: 719
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

If you went with the 31.10 inch tire and the 3.54 gear you would get 52.2 at 2000 RPM.
wmws is offline   Reply With Quote
Old 07-19-2019, 10:48 AM   #9
Y-Blockhead
Senior Member
 
Y-Blockhead's Avatar
 
Join Date: Jul 2011
Location: Redondo Beach, CA
Posts: 5,817
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by mike657894 View Post
Is there a brand I can get them in cheap? around $100. or what do they cost? The speed is probably worth it.
Mike the new Lucas Nokia 5.50-19 can be had for $129. It has a slightly smaller diameter than the Goodrich at 30.50".

It works out to 51.28 mph with the 3.54s, 48 mph with the 3.78s.

Last edited by Y-Blockhead; 07-19-2019 at 11:00 AM.
Y-Blockhead is offline   Reply With Quote
Old 07-19-2019, 11:07 AM   #10
MikeK
Senior Member
 
MikeK's Avatar
 
Join Date: May 2010
Location: Windy City
Posts: 2,919
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

One very slight problem with the above calculations- The measured diameter of a tire is not equivalent to the rolling diameter. Even for tires of the same size, this will vary between manufacturers, construction, and tread.

Many tire manufacturers list revolutions per mile for each tire they produce. That is the most accurate way to figure speed vs. RPM.
MikeK is offline   Reply With Quote
Old 07-19-2019, 12:39 PM   #11
Y-Blockhead
Senior Member
 
Y-Blockhead's Avatar
 
Join Date: Jul 2011
Location: Redondo Beach, CA
Posts: 5,817
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by MikeK View Post
One very slight problem with the above calculations- The measured diameter of a tire is not equivalent to the rolling diameter. Even for tires of the same size, this will vary between manufacturers, construction, and tread.
And of course Mike is correct. These calculations are all on paper and the results will be different in real life.

I just wish I could get that fact into the heads of engineers where I worked (now retired). They kept coming up with these "new ideas" (and I'm sure still do) to make a better product or save money that don't work in real life.
Y-Blockhead is offline   Reply With Quote
Old 07-19-2019, 01:34 PM   #12
Peyton
Senior Member
 
Join Date: May 2010
Location: Jacksonville Fl
Posts: 141
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Years ago, I had a Volvo 122S that could get to 100 with its stock tires (15 inch wheels). I changed to bigger rear tires and suffered loss of gas mileage and performance. Maybe it was the dynamics of that particular car that made the use of larger rear tires counterproductive.
Peyton is offline   Reply With Quote
Old 07-19-2019, 02:16 PM   #13
M2M
Senior Member
 
M2M's Avatar
 
Join Date: Jul 2012
Location: Australia/USA/EU/Soviet Russia
Posts: 1,105
Arrow 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.
__________________

M2M is offline   Reply With Quote
Old 07-19-2019, 02:37 PM   #14
M2M
Senior Member
 
M2M's Avatar
 
Join Date: Jul 2012
Location: Australia/USA/EU/Soviet Russia
Posts: 1,105
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

This thread shows what 550x19 bias ply look like on a car:

https://www.fordbarn.com/forum/showthread.php?t=242572
__________________

M2M is offline   Reply With Quote
Old 07-19-2019, 03:30 PM   #15
sphanna
Senior Member
 
sphanna's Avatar
 
Join Date: Jun 2010
Location: Polk City, Iowa
Posts: 526
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Unread Today, 11:07 AM #10
MikeK
Senior Member

MikeK's Avatar

Join Date: May 2010
Location: Windy City
Posts: 2,804
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio
One very slight problem with the above calculations- The measured diameter of a tire is not equivalent to the rolling diameter. Even for tires of the same size, this will vary between manufacturers, construction, and tread.

Many tire manufacturers list revolutions per mile for each tire they produce. That is the most accurate way to figure speed vs. RPM.


Mike V In my opinion is closest to correct. However I Think the most accurate is to get the distance from the center of the wheel to the ground with the proper inflation air pressure. double that to get the effective diameter. This will be slightly less do to the weight on the tire. I know this is very OCD but that is just me.
__________________
Steve Hanna, Polk City, IA
sphanna is offline   Reply With Quote
Old 07-19-2019, 04:10 PM   #16
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Posts: 2,332
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by 30 Closed Cab PU View Post
M2M

I am running 7 X 16 Tornel bias ply with a 3.54, circumference 30.8 inches.

I have checked speed at multiple side of the road radar displays and am dead on. Went with these because they give me the same results as standard OEM rims/tires.

Picture shows tires, spare is standard rim/tire.

If interested I will go for run and see what speed is 2000 rpm. Let me know if interested and I will post back.


Just went for a drive 2000 RPM = 49 mph
30 Closed Cab PU is offline   Reply With Quote
Old 07-19-2019, 04:45 PM   #17
john in illinois
Senior Member
 
john in illinois's Avatar
 
Join Date: May 2010
Location: Illinois
Posts: 2,181
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Put a mark on the side of tire at the bottom and a coresponding mark on floor.
Move the car 1 revolution of tire and so mark is down. Mark floor and measure between 2 marks on floor.

That is the rolling circumference of the tire. Easy to compute rolling diameter.

John
__________________
Welcome each day
john in illinois is offline   Reply With Quote
Old 07-19-2019, 07:37 PM   #18
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 7,472
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by Peyton View Post
Years ago, I had a Volvo 122S that could get to 100 with its stock tires (15 inch wheels). I changed to bigger rear tires and suffered loss of gas mileage and performance. Maybe it was the dynamics of that particular car that made the use of larger rear tires counterproductive.
The restorer of my '28 Tudor fitted a 3.54 diff. A later owner fitted a 26% Mitchell O/D. I am going back to reduce the overall ratio because it is too highly geared as it is in O/D. Economy is poor and it hates hills. This is the same as you experienced.
By going back to 3.78, I am reducing the overall ratio by about 3.6%. By putting 5.00X19 wheels and tyres on it, I'm dropping by 3% - about the same. I have the wheels ready to go (the old 21" tyres are worn out) so I will try that option first ($$$).Before anyone criticises me for putting 19" wheels on a '28 car, this car is a go-er, not a show-er!
__________________
I'm part of the only ever generation with an analogue childhood and a digital adulthood.
Synchro909 is offline   Reply With Quote
Old 07-19-2019, 08:28 PM   #19
updraught
Senior Member
 
updraught's Avatar
 
Join Date: Feb 2015
Location: Australia
Posts: 1,967
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

Quote:
Originally Posted by Peyton View Post
Years ago, I had a Volvo 122S that could get to 100 with its stock tires (15 inch wheels). I changed to bigger rear tires and suffered loss of gas mileage and performance. Maybe it was the dynamics of that particular car that made the use of larger rear tires counterproductive.
Looks like a small engine. Probably dropped off the good bit of the power curve.

https://www.motorsportmagazine.com/a...peed-volvo-122
updraught is offline   Reply With Quote
Old 07-20-2019, 08:58 PM   #20
Peyton
Senior Member
 
Join Date: May 2010
Location: Jacksonville Fl
Posts: 141
Default Re: changing to 5.50 Bias Ply = changing to 3.54 ratio

i think you are right.
Peyton is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 11:57 PM.