Taller Rear Tires

B

B.SUTTON

Junior Member
I have seen quite a few driver quality A's running 16" '35 wheels with taller rear tire sizes. Has anyone tried a larger size tire on the original 19" wheels. If so, what size did you run? 700-19? 750-19? What is possible with the narrow rim width? Thanks!
 
I've run Firestone 550-500 x 19 on the rear of a 30 town sedan. these tires are larger than the norm and it increases the top end. The 550 tires also look good to me..
 
While there are members here that can help with answers to modified questions another source of answers to modified questions is the sister site HAMB since this site tend towards the stock Model A.
 
So...let me get this straight. Bigger tires on the rear and smaller tires on the front means the car is going downhill ?

Must get great gas mileage as all you need to do is use the brake !

(That's a joke son)

Marc
 
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Gas mileage should be slightly improved. The taller rear tires changes the final drive ratio. Taller rear tires get you closer to 3.54 and can lower engine rpm at a given speed. Actually the 550-500 x 19 was popular for 4 door model A taxi cabs. The normal 475-500 X 19 would be used on the front for easier steering. Its not that noticeable, gives a slight rake but not a hot rod. I would think it a personal choice. I think that a Fordor or town sedan looks good with 550-500 all the way around. One of the regular posters here has a Murray town sedan with 550X19 for his avatar
 
Thanks Purdy! To those who suggested the HAMB, I posted my question there also. I just thought that, while the question is not specific to a 100% correctly restored Model A, Ford Barners would have more insight on the 19" A wheels than the rodders on the HAMB would. And for those who may fear that I am doing something evil to one of Henry's finest, rest assured that my '30 Tudor is not a hot rod. It is simply an old unrestored car that I enjoy puttering around in (and puttering around with). It's had a couple repaints, some incorrect upholstery, and a mechanical overhaul in it's life, but no major modifications from stock.

With that said, does anyone else have any experience running larger than stock tires on 19" wheels? Anyone run anything larger than a 550?

Thanks!
 
Purdy Swoft said:
Gas mileage should be slightly improved. The taller rear tires changes the final drive ratio. Taller rear tires get you closer to 3.54 and can lower engine rpm at a given speed. Actually the 550-500 x 19 was popular for 4 door model A taxi cabs. The normal 475-500 X 19 would be used on the front for easier steering. Its not that noticeable, gives a slight rake but not a hot rod. I would think it a personal choice. I think that a Fordor or town sedan looks good with 550-500 all the way around. One of the regular posters here has a Murray town sedan with 550X19 for his avatar
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IDK if you're talking about me, but I have a murray TS with the 550x19 BF Goodrich tires. I love them. Everyone says the look fantastic, and they have already lasted twice the lifetime of my previous firestones, and they still have tread left. I wouldn't be surprised if I get 20,000 out of them.
 
Yes Jordan, It is your car that I was thinking about. The larger tires do last longer and look great. They also look good on a model A pickup.
 
Purdy Swoft said:
Yes Jordan, It is your car that I was thinking about. The larger tires do last longer and look great. They also look good on a model A pickup.
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I've also seen them on tudors and a vicky... have yet to see them on a car and think they didn't look good.
 
here are some pics
 

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looks good ! I have 3:54 + 5 speed & 31" tall rear tires . 65 is a good speed now ...
 
I guess the question is what are you going after? Looks, (Which I like the looks of the big tires) or performance as in top speed?

If your current tire diameter is about 30 inches, your 550's will be about 35 inches in diameter. That 5 inches will net you about 8 miles an hour increase at 50 MPH. Read that as in when your speedo says you are doing 50 you will really be doing 58 due to the larger ratio created by the larger tire diameter. (Theoretically, in a vacuum with no wind resistance), your results may vary.

Two of the things affect handling/ride performance,are sprung weight and un-sprung weight. Your un-sprung weight is everything from the springs down (including part of the weight of the springs) and the sprung weight is everything above the springs, including to some degree the upper most springs which do not spring as much as the lower, longer springs. So by putting the heavier tires on the solid rear axle you effect that axle's relationship to the road, the suspension, and thus the car, and its reaction to bumps, turns. Braking ability is altered, as well as the torsional loads placed upon the rear axle/radius rods. Corner handling will change as the larger (Radial?) tires (higher sidewall) flex and roll with the shifting car weight. And of course your speedometer/odometer will no longer be accurate.

In addition it would negate some of the additional increase in fuel mileage due to the heavier rotational mass that needs to be over come as well as the friction created by greater road surface contact (wider tire). Very few of those jacked up trucks with those huge tires get any increase in fuel mileage even though the tires are larger in diameter.

I am not smart enough to actually perform any of the cipherin' required to determine the new loads placed upon the vehicle and they may all be moot, as many others have put big tires on lots of cars, myself included. But one should be aware and thoughtful about the effects of the decision, and insure that the related components are in top notch condition.
 
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I found the Goodrich 5.50 X 19 on Coker's site. They are listed at 31.10 " in Diameter, whereas the 4.75-5.00 X 19 is listed as 30.50" in diameter. That would equate to approx. 1 mph extra at 50 mph. or 51 mph. Is there another tire that I didn't find that is larger than 31.10? Jordan's tires definately look bigger than 31.10 inches.
 
So, it sounds like the 550/600s are a fairly common upgrade. I agree that they do look good in the posted pictures. Thank you for that. Looks like they give a 2" increase in dia and 0.8" in tread width over original. I see that Coker also offers a 650 tire but has no specs listed for it. Anyone have any info on fit of the 650 or larger tires?
 
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