Radial tires on original wheels

[ddesjard]

Got a 1950 Dodge Coronet, 4-door, fluid drive trans, 230 ci engine.

 

Currently I'm riding on Remington G78-15 4-ply  polyester tubeless tires on original 15 x 5 wheels.

 

I've been looking at putting radials on my original 15 x 5 wheels.  I had just about decided on 225/75R15--but then I looked at this chart and it seems to say 195 is the highest diameter I should go with.

 

I've done so much research that I can't recall now where I got this--but another chart suggested that 215 was acceptable (and then I stepped it up to 225, based on yet another chart that said it was a larger-than-normal tire, but still acceptable).

 

So--I really want to keep my original wheels and I want the largest acceptable tire I can get (without getting any rubbing in the wheel wells, overly screwing up my odometer, etc.).

 

Not interested in doing any modifications to the car--it's a 90+ percent survivor.

 

Thoughts on the best size radial tire for me?  Thanks.

Edited June 20, 2019 by ddesjard

[Silverdome]

Go look at the Coker Tire website. You'll find a conversion chart there that is accurate. You can go a little larger on width for example 225 instead of 215. Your height aspect will also affect overall tire diameter for example 75 is taller than 65, those numbers represent the percentage of sidewall height compared to the width aspect.

[greg g]

Running 225/75-15 on the rear, speedo off by 3mpg, reads faster than gps indicates. Make sure your spring rubber bushings are in good condition, I had some fender rub when negotiation sharp turns before I put new rubber bushings in the rear spring eyes.

[casper50]

I run coker 16x6 on my original 47 Dodge rims.

[blucarsdn]

I ran P205/75R14 on my '56 & '57 T-Birds for twenty-five years on the stock wheels with no issues. I run 15" radials on my '39 P8. Inflation in the one issue you have to watch, radials are high pressure tires. 32-34 lbs minimum.

[YukonJack]

You also want to watch for wheel flex. The radial tires seem to put more stress on the stock wheels. My 47 Plymouth had stock wheels with radial tires when I bought it years ago. Sometimes when making a turn the front wheels would flex enough to pop off a hubcap and it would go rolling past me. ? 

[Andydodge]

The first number in the radial tyre sizing refers to the tyre width, personally if using a stock 5" rim I wouldn't put anything larger than a 205.......when I ran 15x6 and 15x7 rims on the 41 Plymouth I had 195 and 235 tyres.......on my Dodge with 6" front rims I have 205 width tyres.........the rear rims are 10" with 275 tyres.........lol..........BUT for me 195/205 tyres are what I'd use with 5" rims.........regards from Oz......and Welcome Aboard...........andyd  

[westaus29]

I agree with Andy - after looking at alternative radials for my 5 inch rims, and unable to find wider rims locally, I chose 205-75-15 as the max I would be game to use and have had no problems except ride is perceptibly harder, especially from front end. These are on a later Plymouth - 1955 Suburban ( I also have a '38 Plymouth under restoration but that will have original type tyres) regards Jim

[9 foot box]

   I replaced the 670-15 tires on my 49 Plymouth First edition Business Coupe with 215-75R15. I tried a 205-75R15 and it was an inch shorter than an original wheel. I found a set of 5 Hankook Optimo's for $300, at a big box store, delivered. The spare just fits in the trunk well, it's snug, but drops in. I run 36-38 PSI. The tires came with a narrow whitewall that I put on the inside with the red dot opposite the valve stem, bubble balanced all with an ounce or less.I was able to mount the tires on the wheel without the tire iron on the last wheel ( I was getting cocky) but had to use NAPA RuGlyde, a 16" bike inner tube and a 2" ratchet strap to get the bead to set and pull the tube free and finish filling with air. As an aside, I set the steering box one star notch tighter because it was wandering a bit even before new tires. A $40 alignment on a Hunter system said I was about 1/32 toe in. 0 degrees is ideal, from the book.

[Plymouthy Adams]

If and when you get the radial tires in place and on the car, you will need to align the car for some positive caster.....yes this will add even a bit more drag to your low speed maneuvering but is needed to keep the beast drivable at speed...trade offs on every modification.

[Silverdome]

I am running 215/75/15 Hancooks on my '48 Plymouth.

[BobT-47P15]

I use 215 -75-15 radial B F Goodrich tires from Coker on 1955 Chrysler narrow wire wheels.  I like the look of that size.  And now they make a narrow tread width radial close to size and look of bias ply.  Neither is cheap.

[plymouthcranbrook]

I also have 215 75 on my 52 Cranbrook and have no problems with drivabilty. Air pressure at 35 PSI

Edited June 22, 2019 by plymouthcranbrook

[soth122003]

I'm the same as Silverdome. 215/75/15 on a 48 P-15.

[dale]

Whatever cross references to the originals which were 670-15s I believe.  My 46 ply has Coker  " American Original "  670-15R  and they run perfect.

[thebelvedereman]

I also ran 215 75 15 on my stock wheels on my 48 Plymouth for years, and then I switched to 15 x 7 Mopar police wheels with 225 75 15 on them

[Ernie Baily]

Hello,

I'm running on my 55 Dodge Custom Royal Lancer with the stock wheels. 15x5 with 225-70Rx15 Silvertown Radials on front and 235x70R x15 on rear. I slightly lowered the car because I wanted a "Meaner" look. I now wish I hadn't put the 225-70Rx15 on the front because they steer hard even with the power steering. I should of put 215-75R x15. They are too costly to change( $270 each Coker WWW Silvertown Radials). On my 48 Plymouth I run 670x15 Bias belted Goodyear collector car tires which match the original dealers delivery sheet that was under the back seat when I bought the car. I bought them through Jim Benjammen POC.

 

 

 

Edited June 26, 2019 by Ernie Baily
added copy

[Ernie Baily]

[ddesjard]

Belated thanks to all for your input. I'm going with some 215/75/15 Hancook Optimos.  Getting them mounted this weekend.  Aside from staying on top of the mechanic about the left and right threads on the wheel studs, I want to tell them the lug nut torque setting to use.  But, what setting should I specify? I see some other threads about this topic on this site, but no specific numbers (ft/lbs) seem to get mentioned. As far as I can tell, I have original wheels with original studs and lug nuts. Thanks in advance! 

[Dodgeb4ya]

65 lbs.

[hi_volt]

How do you guys get the 215/75/15 tires to fit in the spare tire well.  I measured the distance from the edge of the spare tire well to the mounting bracket, and it doesn't seem like you can get anything wider than about 7" or so past the bracket.

[Andydodge]

There are a couple of caveats to consider when changing from crossplies to radials..........for me the aspect ratio is a different thing to consider when deciding to run radials....for a stock style 5" wide rim I would not use anything wider than a 205 tyre, irrespective of whether its a 60/65/70/75 aspect ratio..........any wider than 205 on a 5" rim is asking for problems......on a 6" wide rim I'd go to maybe 225, again but thats just me, again the aspect ratio has no bearing on the tyre to rim fitment in this argument.........

..........now as for getting anything wider than say a 195/205 to fit in a stock spare tyre well,  that probably only was made to fit a 6.50 or maybe 7.00 wide tyre is a separate issue and is something thats an entirely different problem........a large hammer may help but apart from a bit of cutting, widening and welding I don't know of any other way to solve that issue other than using a tyre that fits but maybe slightly narrower that the other 4 on the car .............again this is only MY Oz 2 cents worth......which is probably only 1.5 US cents worth................lol.........Andy Douglas 

[Silverdome]

My spare is a 205/75/15 and just barely squeaks in the well area.

[Plymouthy Adams]

get a smaller tire for your rim...they are available....we all like spare to match the rubber on the ground but sometimes we have to make concessions....the spare is just that, spare...

Edited July 15, 2019 by Plymouthy Adams

[Eneto-55]

I've sometimes wondered if anyone has gone the route of widening the spare tire tub, but I would guess you couldn't go much at all before you would need to either move the gasoline tank to some other spot, or get a narrower one made to fit.  Lota' work for a tire & wheel you hope to seldom if ever use.  I won't consider it, because I have no plans to use a wide tire.  (Almost bought a set of 16" wide white walls way back when I got this car - $100.00 for the whole set of 4, off of a Jaguar.  Good thing my dad stopped me though, considering that this was back in 80 or 81 or so....)