Widest wheel and tire combo for a 49 special deluxe convertible

[STX123]

Hi everyone, I searched to find the answer to my question before I posted, because I’m sure this has been discussed, but could not find an answer, so sorry, but here goes. 
I have a stock 49 Plymouth special deluxe convertible P18. I want to finally change over to radial tires. My rims are shot, so I want to get new wheels also. What would be the widest wheel and tire set up I could run in the rear, and front?  Any suggestions are welcomed. 
Thank you. 

[greg g]

It has been reported that 15 inch 7 inch wide poice spec wheels will work.  The backspace can only be 3.5 inches.  The 7 inch wide rims will work with 60,70,75 series tires, however there might be a interference problem with the steering knuckle with some fitments.  Are you planing to change over to studs and lugnuts or are you going to keep th e bolts?  You know one side is lefty tight I assume.

[Sniper]

I can't give you an specific answer, but I can show you how I sorted it out for my 51.

 

http://www.yourolddad.com/tires

[Andydodge]

When I owned this 1941 Plymouth I fitted Wheel Vintique standard backspace Chrome Smoothies, 15x6" and 15 x 7" front & back with Coker Classic Whitewall radials in 195/75x15 front and 235/75x 15 rear.....the car was also lowered with 2" blocks on the rear spring and 1 coil cut from the front springs..........I had no issues as far as clearances front, back, inner body outer wheel arch or fender.......car rode and drove much better and I was happy............not happy when I sold the car 7 years ago........andyd  

[Loren]

In my research Greg G is correct the max backspace is 3 1/2 inches (this is what the stock '49 wheels are and you can't go more because things start bumping) which means any increase over stock width goes to the outside. There seems to be plenty of room for wider rims in the fender openings as long as you don't go too large on the tires.

One thing usually over looked is the hub diameter, most after market wheels are around 1/2 inch larger in the I.D. than the Mopar hub O.D.. I don't know if you care about that but I do.

6 to 7 inch wide sounds about right but if you are using over 205/75/15 tires, (the modern radial equivalent to the stock size) a test fit would be a good idea.

Another thing to remember is the wider the tire the greater the steering effort will be when parking. Radials typically like more caster than the Plymouth can be adjusted for but considering the advantages Radials have I don't think 99 out of 100 owners would care.

 

Great looking car Andy!

[STX123]

To all,

I cannot thank you enough for taking the time, and sharing your info. Now I have ideas that I can try out. My head started hurting with the whole math thing tho. Just like back in math class. Lol. Great idea with the wood block. The cars really look amazing just with a wider tire setup. I’ll keep you all posted on how I make out.

 

Thanks again,

John

[greg g]

The back space measurement  is the depth of the inside rim of the wheel to where the center bolts to the brake drum.  Put a straight edge across the wheel and measure down next to one of the lug holes.  You may be able to fit 3 3/4 but that's about it. I have 15 inch aftermarket wheels that are 5.5 inches wide they carry 205 75 15 in the front and 225 75 15 rears.  With a load in the trunk, the right side used to rub on left hand turns.  New rear spring bushings and shocks cured the problem.

 

 The wheels are wheel vintage smoothies.  They won't accommodate the stock hub caps.  Running trim rings and baby moons.

[STX123]

Greg G, that looks awesome. I never thought about the stock attaching bolts. Do the newer rims work with the stock bolts? Is there a conversion kit to install studs, or do you just bang them in like regular modern cars? 
 

Thank you.

[greg g]

These wheels feature GM and AMC, Ford, Mopar bolt patterns. When using the stock holes, one of the gmc holes accommodates the alignment pin.  Switching to studs would entail having studs pressed into the drums Fram behind after r e moving the drums.  Or maybe the rears need the axles pulled and the the studs pressed into the flanges.  It's doable but the question becomes why bother.

[Frank Gooz]

I have a 1950 Dodge Coronet. at one point i had 225-75-15 on a 7 inch wide wheels at recommended 40p.s.i. and the steering was i little tougher the present.

I now the same tire size. 225-75-15 on a 5 1/5 wide wheel at a recommended 44p.s.i. with much easier steering.

Hope this helped. 

[Adam H P15 D30]

 

 

15x7 with 3.5 inch backspace - 205/60/15 front tires aired up to max sidewall pressure 

15x8 with 4 inch backspace - 235/60/15 rear tires aired to 35psi 

I do have an 8" Ford rear axle which was slightly narrower than stock.  No tire rub.... ever

[STX123]

Thank you all for the great pics and suggestions. I always loved the wider tires in the back look. Now just have to make rim choice. Thanks for taking the time to post, it’s much appreciated. Thanks again everyone. 

[STX123]

Hi Everyone, can’t believe it’s been 3 years, but that’s life. I’m back on the Plymouth. I ended up cleaning and using the stock rims and went with 205/75/15’s. It made such a difference. The car is not all over the road anymore, and I feel safe and actually enjoy driving it. I cheated and went with Portawalls. I couldn’t do the $320 a tire for a car that mostly sits. So $400 for tires and $100 for the Portawalls. If you ever tried installing them, you know it’s a bit of a challenge until you get the feel. 
Thanks again for the help! Now off to get info on how to get another gear! Jeeze, at 50MPH she’s screamin. 

[Loren]

How to get another gear?

The easy answer is a mid 1952-55 ( 56 is 12 volt ) Plymouth Automatic Overdrive transmission. Turns a 55 mph car into a 70 mph.

Uses the same shift linkage, same parking brake, the speedometer gear transfers from your old 3 speed and if your car is 118 inch wheel base it uses the same drive shaft.

If you have a 111 inch wheel base you will have to make an extension rod for the parking brake and shorten your drive shaft.

If you drive at 55 mph it makes the engine so quiet you’ll think your going 35!

Check your rear end gear ratio by looking at the flat section under the fill plug, 3.73 works very nicely.

[andyd]

STX....looks nice tho' I'd be throwing some chrome hubcaps on the wheels but thats just me........with or without its nice.........andyd

[STX123]

Loren, thank you for that information. I’m definitely looking into that. Although, I loved it when my Daughter asked what I was doing when I was column shifting the car. lol. And no Bluetooth radio?! 
 

Andyd, Thank you, and 

I do have the chrome hubcaps, that’s why I stuck with the old rims, but after spending like two weeks wire wheeling, sanding, and painting them, I’m leaving them exposed to look at them for awhile. lol. 

[JerseyHarold]

21 hours ago, STX123 said:

 I ended up cleaning and using the stock rims and went with 205/75/15’s.

I'll eventually need tires to replace the rotted 'rollers' on my car now.  What brand did you get and where did you buy them?

[STX123]

They are Hankook Kinergy ST

$97.99 from Tire Rack. Online. 
SL rated.
$425.77 with tax and delivered to my door. 

205/75/15.  

[JerseyHarold]

Thanks for getting back to me.