tire width for DeSoto Suburban

[DonaldSmith]

I've been running 205-75R15's on the car for 14 years.  They still look good, but continuing to run them goes against conventional wisdom and the vested interests. 

I know. this is like which oil is best. 

 

14 years seems a little long in the tooth.  It's only 75 miles from my house to the Desoto Convention in Chatham, Ontario this fall.  I'm mulling over popping for some modern whitewalls, like the present set. Maybe $600 for peace of mind?   Or risk a blowout, and see of Mother Mopar's wheels steer straight like the old commercials, and whether Canadian Tire would treat me well.   

 

Instead of 205s, would the narrower 195s look more vintage?  The charts say that they will fit 15x5 wheels.  Maybe the smaller footprint would handle better?  or worse? and put more or less stress on the wheels?  (I added power steering, so parking is no problem with the 205s.) 

 

Another thing to throw in the pot is the curb weight of the car, 4,000 lbs plus contents.  

 

Thoughts? 

 

 

 

 

 

 

[soth122003]

This might help. Also there is a thread currently on page 1 with the header "tires" that might be of interest.

https://tirepressure.com/tire-sizes 

I checked the P195/75r15 @ 26 psi will support about 1279 lbs. each tire. 32 psi supports 1411 lbs. each

 

Joe Lee

Edited May 16, 2023 by soth122003

[greg g]

I ran 205 75 15 on my p 15.  They rode and handled OK but overall diameter was short, making the speedometer 7 to 8 mph off.  For around town it wasn't a big deal but for road trips it didn't suit how I wanted the car to work,  so I put a pair of 225 75 15 on the rear. If I remember the original  tires were 600 16s with a 28.5 or 29 inch overall diameter.  The 205s were 27 and the 225s are 28.75.  This relaxed rpm a hit and corrected the speedo to 55 indicated was 54 on the gps.  Yes they look too fat, yes there was some rub on sharp turns (new shakle bushings fixed that) but now I have tires I can replace just about anywhere I am with in stock off the shelf tires from wally world, costco, bjs etc.

 

The fronts were mounted in 2005, the rears in 2007.  So I am overdue age wise, but the front are at 1/4 tread wear and the rears still at half or more.  The current fronts were in storage till two years ago as they were take offs when I put the 225s on the back. The 205s are uniroyal tiger paws, from W mart,the 225s are cornells from pep boys.  The unis were $ 55 each, the cornells were 5 bucks more.

 

Ah the good old days.

[DonaldSmith]

Do I look fat? 

 

 

Those are 205s.  Anybody have 195s?  Maybe they would look too thin?    These are the cheap, every tire store has them, whitewalls.  I'm not going wide whites.  We won a raffle at a DeSoto convention, and we bought the stainless steel trim rings.   Snazzy enough.  The big issue is whether I should replace 14-year old tires that still look good.  Does garaging the car have any effect on the tires aging?   I know that some RV campers have covers for their tires. 

 

I would get radials again.  Better ride.  Power steering takes care of parking.  One specter hanging over the use of radials is the fatigue cracking of the wheels.  Has anyone experienced this?  If I pop for tires, I would ask the shop to inspect the wheels.  If they are faulty, I would have fun finding replacements. These are heavy duty 7-passenger wheels, that take special hubcaps.    

 

 

[Los_Control]

Sure is a tough call, I doubt anyone here has a crystal ball to gaze in and tell you the future of your current tires.

 

Rule of thumb is the rubber starts to age & deteriorate at 10 years. ..... Even if still on a tire rack in the store & never installed.

 

My personal opinion, if they were 10 years old & in the condition yours are, they would probably be fine ..... but 14 years? Who knows.

 

I think if there would be a problem, it would come from a long drive & heat build up. ..... As the rubber slowly deteriorates over the years, then add heat to the compromised rubber.

 

Around town probably could be fine, on the freeway thats where they would fail if at all.

 

Concrete is the same way, it is good for up to 100 years, depends on who mixed it. Then it just deteriorates every year & gets weaker & weaker until it just crumbles into dust.

Your tires have reached their life span @ 10 years, now just getting weaker as time goes by.

 

[soth122003]

I have had the tires on my P-15 for about 10 years. When I first got it the tires were crap. Old and cracking on the sides. One night we heard a sound like a shotgun blast. Looked all over, even the neighbors came out looking and we couldn't find any problems. On the way back into the house i saw the car was sitting angled and found the right front tire had blown out at the side. Gaping blow out about 5 inches long. Scared the bejesus out of the neighbors thinking some one was shot.

 

The tires on my RV when I changed them had over 16 years on them. The difference between the 2 was the RV tires had started to develop the sidewall cracking (not big about 1/16 of an inch kinda crackling). That's when you know you have to change the tires. The UV rays from the sun are the biggest killer of tires that don't get much mileage.  When I changed the RV tires they only had about 20,000 miles on them. They were the expensive Michellans and had 90 percent of their tread still on them. Hated to change them but a blow out in a front tire of an RV at 60 mph is catastrophic. 

 

If you kept your car garaged and out of the sun and there is no sidewall cracking they should be ok. The sidewall is the weakest area of the tire when age is the factor.  You can probably pull a tire (suggest the front) and break the bead and inspect the inside for cracking and damage. If none is found reseal and make it a annual inspection. Or you can just change the tires for peace of mind. Just depends on luck, driving skill and pocket book. If you drive interstate a lot change them. Two lane roads and slower speeds your call. 

 

Just my 2 cents worth, like most pennies now a days not worth much, but there you go.

 

Joe Lee

[joecoozie]

The standard original size for your car was 7.00X15 which converts to P215/75R15 or P225/70R15

I would not go with the narrower tires especially with a car that large and heavy.

(BTW - I had a 47 Suburban years ago and I really miss that car)

[Los_Control]

@soth122003 I think you have some very valuable points with experience.

Just now, soth122003 said:

The tires on my RV when I changed them had over 16 years on them. The difference between the 2 was the RV tires had started to develop the sidewall cracking

We really cant compare 4 ply automobile tires with 10 ply RV tires. ..... The thickness of the rubber casings, The diameter of the steel sidewall cables .... The thickness of the inner liner they are built different.

Typical 4 ply car tire has nylon sidewalls, cheaper & smoother ride. ..... Like comparing apples to oranges.

 

Just now, soth122003 said:

If you kept your car garaged and out of the sun and there is no sidewall cracking they should be ok. The sidewall is the weakest area of the tire when age is the factor.

I will disagree here ... very politely of course. I have found over the years it is the layer of rubber that is between the belts of the tire that fail.

 

I spent 15 years retreading semi truck tires .... When I left the field, I was the manager of a Bandag retread shop .... If we had a tire that failed, it was my job to inspect it & see why it failed.

We generally just replaced for free just to keep the customer happy. Sometimes it was just too obvious they picked up a nail, ran the tire low & it came apart from heat.

The belts separated, the tread came off ..... Sometimes it wiped out the fenders & tail lights <---- @DonaldSmith

It was my job to see if we would pay for the damages. .... Sometimes we did .... Fact is, you have a large account like swift trucking ..... they got a problem, let me fix that for you .... Keep the customer happy.

 

It is heat that kills tires. The belts separate the tread comes off ..... Rarely is it the sidewall that fails, but does happen on a compromised tire.

[soth122003]

47 minutes ago, Los_Control said:

I will disagree here ... very politely of course. I have found over the years it is the layer of rubber that is between the belts of the tire that fail.

I'll buy that for a dollar...with an exception. The use of the tire. If it is used constantly like on the every day driving (big rig or car) then you have the heat cycle and the wear cycle working together to wear the tire down inside and out. Tires that aren't used that often will last a lot longer if kept out of the sun, hence wheel covers for the RV tire or garaging your car. Two keen examples of UV damage is the clear coat on car after a few years and plastic in cars that is exposed to the sun. 

 

51 minutes ago, Los_Control said:

We really cant compare 4 ply automobile tires with 10 ply RV tires.

Didn't think of that when I made the comparison. The crux of my statement was with the tire exposed to the sun. 2 ply 10 ply 1000 ply the result is the same. When a tire sits out in the sun the UV rays basically boil the oil out of the rubber and kill the tire. Just takes a while and the common driver does not inspect the cars very well.

 

57 minutes ago, Los_Control said:

The belts separated, the tread came off ..... Sometimes it wiped out the fenders & tail lights

That's the one thing about the steel belted radial, pull over quick or else. The ply bias tire usually came apart from the rim riding on it an cutting it to pieces. Of course the way every one drives now just changing lanes is an accident waiting to happen. LOL

[Los_Control]

Just now, soth122003 said:

I'll buy that for a dollar...with an exception.

I agree with everything you said.

I have no experience with tires 10 years old .... Checking the date code is the very first thing done on inspecting a casing before retreading ....

If they were even close to 10 years old, we just marked them RAR ... (return as received)

 

So it is understood, I'm only offering my opinion on tires less then 10 years old. .... I do not have a crystal ball ..... What happens if a tire separates on the freeway and damages a fender?

It can cause metal & paint damage ..... How much does that cost to repair on a Desoto? .... Me I have a truck & a hammer.

 

I spent a lot of time with tires, anything over 10 years old we just did not mess with .... I was sent to school many times over the years .

Classic cars & 14 year old tires never was brought up.

[soth122003]

Thanks for words Los. 

 

Something else to think on as well is the planned obsolesence of parts and items made today. Make cheap, make it fast and make it not last as long so people will have to buy another to keep the business growing and the money rolling in.

Of course when you really think about it, our cars were built like tanks and made to last. So short of crashing due to a flat or blow out, I don't think our cars will take much damage from the tire itself unless your on the freeway doing 70 plus mph then all bets are off.

 

Joe Lee

[Los_Control]

Just now, soth122003 said:

Thanks for words Los. 

Let me tell you a sad story with a happy ending.

I hate seeing my neighbors car sitting like this, his health is returning and someday he will be home.

Has a 302 FI motor with a AOD transmission .... Will cruise 80 mph all day long.

 

It is the old bias ply tires with the wide whites ..... They look nice, they are great for parades ..... would I drive the car on the freeway with the old tires.... even though they look good? ..... We all need to make that call at some point or another.

 

 

 

[kencombs]

5 hours ago, Los_Control said:

Sure is a tough call, I doubt anyone here has a crystal ball to gaze in and tell you the future of your current tires.

 

Rule of thumb is the rubber starts to age & deteriorate at 10 years. ..... Even if still on a tire rack in the store & never installed.

 

My personal opinion, if they were 10 years old & in the condition yours are, they would probably be fine ..... but 14 years? Who knows.

 

I think if there would be a problem, it would come from a long drive & heat build up. ..... As the rubber slowly deteriorates over the years, then add heat to the compromised rubber.

 

Around town probably could be fine, on the freeway thats where they would fail if at all.

 

Concrete is the same way, it is good for up to 100 years, depends on who mixed it. Then it just deteriorates every year & gets weaker & weaker until it just crumbles into dust.

Your tires have reached their life span @ 10 years, now just getting weaker as time goes by.

 

Funny you should post the concrete info as I was just reading this:

https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106

very interesting.

[Los_Control]

Oh @kencombs we cant go there. I then would have to explain the creation of man ..... Yeah buddy .... not looking to get kicked out of here that fast.

[Sniper]

Not sure I can comment as I am running P255/50R17's, lol

 

 

[kencombs]

11 hours ago, Los_Control said:

Oh @kencombs we cant go there. I then would have to explain the creation of man ..... Yeah buddy .... not looking to get kicked out of here that fast.

Color me confused.  How  would concrete formulation get us kicked out of here?    Nothing political or religious involved.   Just slaked lime vs hot mix and how it effects concrete life>

[DonaldSmith]

I've decided. 

 

I'm buying 4 new tires, just like the old ones.   

 

I'm keeping the spare.  I know it doesn't matter, but they have never been run.  If I need to use the spare, wit will be at low speed and short distance.  

 

Thanks for all the input.  (I designated the reference to the "tires" thread as "solved", because of much discussion there on old age of tires.)