Wheel size discrepancy

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So I have a flat tire on my 32 model 54, and I removed my spares from the fenders to find that both spares are 18in rims. All 4 wheels on the the car are all 17in rims. All 6 wheels have  identical design. What is going on here? Is it common for the spares to be a different size?

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If I recall, 17 inch wheels didn’t arrive until 1933.  There then was a difference in the wires that changed by 1936 (perhaps ’35) with the 33’s having a concave rim edge, and the later ones being convex

 

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Tony is correct as usual.

Unless you want to chase trophies, I’d stick with the 17″ on the ground. You will have a wider contact patch and higher weight load capacity.

The 18″ will fit the spare tire covers, but the 17″ will not. If you were to go to 18″ wheels and get new tires, 7.50 x 18″ will give you a slight advantage in diameter and load capacity over 7.00 x 18, but would probably not fit the sidemount covers.

Whichever way you go, give me a call if you want to change tires and I’ll tell you about my experiences with tire size for 1931 to 1937.

 

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Tony, thanks for the 411 on the wheels, but now the mystery of how 17s ended up on the car is nagging at me.

David, I don’t plan on chasing trophies and I will take your advice and continue rolling on the 17s. I will just buy a new 17-7.0 tire and tube. The 18in tires look brand new, one is a Lester white wall and the other is a “gum dipped” Firestone. Thanks for the

 

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Ryan,

I suggest using 16″ radial Truck tubes to avoid crease3s, also the quality is generally better for our heavy cars.

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I agree with running the 17s, and 700×17 (not 750s which were for 12s).  I strongly endorse Dave Stevens’s concept of running 16″ radial truck tubes, available from your modern tire wallah, with the 17″ wheels, due to the drop-center wheels.  The “repro” tubes are junk, and I had two fail within 1500 miles on the bonded seam, not on any possible friction point.

Use flaps OR use HVAC high-temp tape (20 mil on the center, 10 mil on the shoulders–ask Greg Long for details).  While tires are off, remove any rust, chemically treat with Metal-Prep or similar, and brush paint some anti-rust paint on the inside of the wheel.

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Follow-on to answer Ryan’s question why the road wheels’ size was changed:  5-lug 18″ wheels were hard to find, and tires were even harder to find a few decades ago.  For 1931 only IIRC, 18″ wheels were 6-lug.  One available 6.50x 18 tire (Excelsior) is IMHO too small in cross-section for road wheels but would be suitable for covered spares in fenderwells.

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Be careful as there are even differences on the 12s.  I blithely ordered 6 750x17s for my 1933 1236, as the car was running on a set of 750x17s, and things were going along fine until I tried to change the spares.  Much to my surprise, the spares were 700×17.  the 750×17’s would not even fit in the tire wells, and forget about the tire covers.  I had to return two of the tires, and get 2 700x17s for spares.  The tires that were on the car looked fine, but I replaced them as they were approximately 45 years old and I didn’t trust them.  I purchased a new Milwaukee cordless tire inflator to pump up the spares in case I had to use them as the tire covers would not fit when they were fully inflated.  The Milwaukee unit runs on their rechargable 12v power packs, and it seems to have a lot of grunt.  I’d take a couple of spare batteries and a charger along on a tour just in case.

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Ken, this is a common situation among all marques, as reproduction tires available today seem to be larger dimensioned in both diameter and width.  Some favored reproduction tires (Bedford, BFG) seem to be the most problematic.  Lester tires seem to be truest to original dimensions.  It is very common to step down a size (e.g., 750 to 700) for sidemounted spares.

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Actually, I think it might be more of one of those things reflecting the individual nature of our cars.  Looking in the specifications in my first Pierce reference, Maurice Hendry’s 1971 Pierce Arrow, First Among America’s Finest.  Hendry lists the standard tire size on the 1236 as 7.00 x 17, and the 1242 and 1247 as 7.50 x 17.  According to the book the 1242 and 1247 also have adjustable ride control shocks, which my car does not have.  I also have an unusual heater on my car, a forced air system that picks up the heat from the exhaust system.  I understand they were common on Cadillacs and LaSalles, but not too common on Pierce Arrows.  My car might be different as it was a West Coast car, which I believe was purchased new by the Steinfeld Department Store family of Tucson.  The car stayed in the Tucson are until the late 1980’s.  In any event, those wide whitewalls look great on the car!

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David,

Thanks for the 16 truck tube suggestion. I was just about to buy some new tubes from Universal this week and I thought I should check on this forum again.

George,

1. I will clean up and paint any rust I encounter and I will apply HVAC tape around between  the tube and tire as you indicated. I am not surprised the wheels were changed out at some point with the cars weight, historically poor roads, and weak tire structure. I did find out that the 17-7s will not fit the spare tire covers but the 18-5.50 will fit. The 18-5.50 look like bicycle tires.  I am learning a lot about Antique car technology and how remarkably different it hand rim modern vehicles. In some ways the technology is more complex and other ways it is simpler. Thanks again to all of inputs and suggestions.

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Hi Ryan, it is not unusual to find 17″ tires on a 1932 car.  Like George Teebay wrote, the 18″ tires were hard to find for many years, and the same lug and spoke pattern wheel in 17″ was in use from 1933-1935 on 8cyl cars.  The V12’s usually had the 17″ rolled rim instead of the common-to-us concave rim.

17″ Bedford Custom Coach tires are usually available in 7.00 and 7.50 size,  White, Black and Double-White walled.  The Bedford tire has an authentic look and are VERY well made tires.

I might have an individual 18″ tire for a spare, if you are still looking.

I also have the high-temp HVAC tape, in both thicknesses.  You CAN use just the 10mil thickness.  Just make sure you are in a warm room when you wrap the wheel in the HVAC tape,  it will conform to the compound curve of the drop center rim very nicely in 70* and up temperatures.  If you are wrapping the rim in cooler temperatures, a bit of careful use of a heat gun or hair dryer will help.  The idea is to cover the welded ends of  the spokes on the inside of the rim, to prevent the tube from abrading against the irregular surface and possible sharp edges.  BUT also to provide a slick surface on the sides of the drop-center for the tube to gently slide down into the drop center as it inflates.  Without the slick sides, the drop center becomes an area where the inner tube is stretched very thin.  It was in the drop center where George Teebay’s new tubes split on the molded-seam.  The replacement 16.5″ or 16″ truck tube or radial tube sits deeper into the rim and is not stretched thin in the drop center.  A bit extra ‘work’ to get the smaller inner diameter of the tube into the tire when assembling the wheel, tire and tube.. BUT well worth the effort.

You are welcome to call me or email me for additional information on tires or tubes or HVAC tape.

Greg Long

 

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Bravo, Greg!  Do I see a future Service Bulletin article in the making?

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