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Truck tire vs car tire question

J

JDemaris

Well-known Member
I'm wondering if anyone has noticed a difference between how rugged car tires are as compared to truck tires . Especially in regard to getting flats on bad roads, sharp gravel, etc.
The reason why I'm asking is - I'm getting a small motorhome ready for a long trip. The tires on it are 15 years old and show a lot of rot-cracks in the grooves of the treads. No cracks in the sidewalls.
This is an RV based on a dual rear-wheel 1 ton Toyota. The OEM tires are an odd-ball D-range truck tire, size 185R-14C(C for commercial). They are $110 to $120 each and I need six of them.
I can get car tires much cheaper that are the same physical size. 195/75-14. $50 each!
So - I cannot make up mind what to do. I hate wasting money but also hate to corners if something is critical.
The RV has a GVW of 5500 lbs. I'd had it on a scale. The rear weighs 3,060 lbs. The front weighs 1800 lbs.
So - two OEM D-range tires have a load capacity of 3500 lbs. Two car tires have a load capacity of 2800 lbs. Again -there is onlyh 1800 lbs. on the front.
The rear with four OEM tires has a load capacity of 7000 lbs. Four car tires have a load capacity of 5556 lbs. The actual weight on the rear when loaded is 3,060 lbs. I'm wondering why the heck I can't get by with the car tires? Any comments or things I've overlooked?
 
I drove a Toyota steak bed with duals for a couple hundred thousand. I put car tires on it recommended by my tire shop. He said pump them up to fifty if you are going to load it with dri wall or such. I ran them in the thirties all the time. If I overloaded the truck witch happened a few times I put 50 in them. It drove road wonderful loaded or empty.

I vote car tires. All season radials.
 
John,
I'm no expert here, but you have done the math, and it seams that the "car" tires will handle the weight fine and probably disipate heat better, reducing the problem of over inflation. However your little camper may not handle very well when you are crusing down the interstate, batteling strong cross winds.
Loren, the Acg.
PS are you headed back to Worster?
 
had a ford f 150 that i used as a camper hauler
camper was a 12 ft slide in unit that sat in the bed of the truck for 7 yrs
had uniroyal tiger paws on it 235/75-15
put more than 50,000 miles on them never a problem
better ride as well
i wouldn't worry about putting them on again
 
Yes, headed back to Worcester. Then on to Indian Lake (Hamilton County) and hopefully get my cabin finally done this summer. I started it 11 years ago. Been in Michigan for 6 months. Hope my house is still there and the pipes aren't broken. Heated with wood for 20 years and this is the first time I ever tried draining the pipes and leaving it unheated. One good thing though. I had a full year's worth of firewood cut that I'll now have for next year. This will be the first time in 20 years I had all my wood cut and stacked this early. I usually get it done in August or September. In regard to the posts on the tires so far - makes me feel better about saving nearly $200 on the car tires.
 
Is that the Toyota with both rear rims welded together to make 1 rim? It has been probably 20 years since I worked on 1, going by faulty memory here. If it is, I don't think there will be enough room between the sidewall bulge, when loaded, between the 2 rear tires, to use car tires. The truck tires have a straighter heaver sidewall. I do remember running into this situation, I think the guy ruined 4 new car tires, he had driven about 60 miles. I do remember it being a job to mount 4 tires on those rims and trying to balance them. I've worked on several of them.
 
Don't let them talk you into bias ply tires you want radials

The trailer guys kept trying to talk me into bias tires for my trailer. Stiffer handle the weight better dont sway etc etc

All crap. Radials run cooler handle the load better and don't sway like they tried to scare me with

Best decision I made was to go with radials

As long as it will handle the load I use them

Here is a good practice check the tired whenever you stop. If they are heating up something is wrong. Low air pressure, can't handle the weight etc

If you let the tire get hot it will eventually fail

Good luck
 
my thaughts 15 years out of the $110 tire. that is $7.33 per year. A $50 tire may get 3 or 4 years. $50 4 years is 12.50 per year 3 years is more per year.
 
No. The Toyotas with "fake duallies" had two Ford Ranger 5 lug rims welded together and bolted to a 1/2 ton semi-floating rear axle. After a big class action lawsuit - the 20-21 foot Toyota RVs sold from 1986 and on came with true 1 ton full-floating rears with real duals. 6 lug wheels with a rare 7.25" bolt circle like old IH and Studebaker trucks used to have. Many older ones got retrofitted with the FF rear but the front was left as is. So those things need two spare tires. One for the front and one for the rear.
Here's some photos of a real FF Toyota rear with duallies. Photos are a 1987 U-Haul 1 ton box truck I stripped. Same setup as used in 1986 and newer motorhomes.
a153550.jpg

a153551.jpg
 
John,
Wish you the best of luck at your home in Worster. It's been extreamly cold here all winter with not much snow. Hope your neighbor care taker monitored things well. perhaps when you head to Indian lake, the wifey and I can make a Sunday ride up there and meet you.
Maybe, Bret and Zack could also drive over if you are willing to be a host. Your call, not trying to put you on the spot.
Loren
 
I'd agree if things really worked that way. The problem is - I don't know. Most of the RV tires I've had to replace were ruined from age and rot, not wear. HD truck tires can rot just as fast as cheap car tires. Rot time is determined by the rubber compound used and how long tires sit unused. Not about how many plies the tires have. The tires on this RV now look like new from a distance and there are no cracks in the sidewalls. But inbetween the raised ribs of the tread there are deep rot cracks.
In regard to radial versus bias-ply -I'm only talking about radials. D-range radials with a 6 ply rating versus passenger radials with I suppose a 4 ply rating.
Also in regard to 15 years out? Hey - by then I'll be near 80 years old and I'll be glad if I'm even still alive. I hate to see things like that - but I guess it comes with aging.
 
No, not putting on the "spot" at all. We just need to get home and figure out what we're doing. Winter has been miserable here in northern Michigan. We never had a single big snow storm - but it seemed to snow nearly every day for a few months. 3" to 5" each time. The locals here say it's the worst winter on record. I was plowing two times a day at times. We also had a lot of minus 20F days. More then I've ever seen in Worcester, NY. Indian Lake, yes. Some people here still have frozen water lines. Lake Huron is still frozen over here. The big river (Thunder Bay) I'm living on just lost its ice a few days ago. Certainly no frogs croaking yet. I have been seeing some ticked off looking robins. One photo is the only open water I saw around here on Lake Huron yesterday. The other is the Thunder Bay River behind the house we're in.
a153554.jpg

a153555.jpg
 
My company vans used to be 1/2 series vans, and because we are a huge company worldwide, accountants make the calls on a lot of stuff from behind desks. Every time that I needed new tires, and there were lots of sets of new tires because "P's" don't hold up like "LT's", or they wouldn't be "P's". Half tons are rated for "P" (Passenger Car), and that's what I always got, overloaded "P" tires that I had to white knuckle year after year after year as winds blew it around the lanes like a snake as the sidewalls offered little or no support. The last set of tires that my last, now retired van got was a set of LTs (Light Truck) only after the GoodYear guy called our fleet office, told them what the truck weighed empty and loaded, and told them that they were looking for a lawsuit if well under rated "P's" blew under stress, and someone got killed. The company retired the van a few months later, LT's hardly used. Truth be told, I service a lot of state police posts and seriously contemplated having them do me a favor and throw it on portable scales, then paddle lock it in their lot and call my company and tell them to send a tow truck. I seriously considered it. These days, my company van is a 2014 1-ton, and it certainly doesn't have "P's" on it. "P's" on anything beyond a Buick? Not me. After decades of white knuckling, not me. Even the barn Jeep has LT's on it, and its a 1/4-ton.

To each, his or her own. Cost versus ??? Much good luck. I'm not going to tell you what to do, but since you asked, that's my experience and opinion from my experience, for myself.

Mark
 
I generally run Michelin tires on my wife's car and my F250.
The sidewalls on the car tires are usually full of small cracks in 5-6 years. The sidewalls on the truck tires didn't start cracking until 8 years. The truck ALWAYS has a load on it too. I'll be replacing the truck tires next week. I'll get the same model Michelin tires as what's on there now. I replaced the car tires last year. I wasn't happy with the sidewalls degrading so quickly on the last few sets of Michelins so I went with Cooper.
If I were in your shoes I'd bite the bullet and put Michelin LT tires on that rig.
 
There is no reason I can think of not to run P rated tires as long as they are of the proper load index. LT tires are reinforced to allow more air pressure to haul heavier loads without causing too much sidewall flex. Since your weight will be relatively "fixed", you can figure the load rating as you have and purchase adequate P rated tires.
 
I don't see any reason to not use the car tires if their load rating is within the necessary range for the camper... You probably won't get as much life from the car tires but I doubt that's a big factor for all the travelling you want to do?

Rod
 
I have attached a photo of the sidewall of my truck tire. It is made for either single or dual wheels. However, notice that it is de-rated by 224 lbs per tire when used in a dual configuration. The unfortunate side of the P tire is you never know what the de-rating for duals would be since I am sure there is not a chart for that. Lets make a guess at it:
3416/3640=.938 or about a 6.2% reduction per tire. For the truck tires.
Lets take it to 7% for the P tires the two tires have a load rating of 2800 lbs or 1400 lbs each. If we are guessing correctly reducing the rating of each by 7% gets us a dual rating of 1302 lbs each or a combined rating of 2604 lbs almost a 200 lb drop per side. Just something to think about.
My personal preference is to have as little rear end squirm or slew as possible; if there is too much it just feels squirrely and on a long trip that will get tiresome fast.
a153585.jpg
 

You really need to analyse the rims and distance between the rims before you can change tires. As said earlier, your tires can rub together if not enough cleanance.. especially when a bit low and hitting bumps.

So.. first question is not what kind of tire, but should be will the chosen tire and rim combination have the correct clearance... the load rating.

Most motorhomes are loaded up with all kinds of junk, supplies, groceries, clothes, tools, and then people, water, and sewerage... So be sure the tires are rated about twice the empty weight. so load rating would be next on the list.

Then look at the choices left and see if a truck tire or car tire makes more sense. Truck tires can be overinflated more than car tires and can take more heat at a rated load. Not saying they are better but the dot ratings are different and require truck tires to handle load and heat under more variances than car tires..


Good luck either way.
 
That is exactly the opposite of the way he needs to go. The aspect ratio he suggested was 75. Going to a 70 is making it a lower profile wider tire. A 195R14 is narrower than a 195/75R14. These tires are designed specifically for carrying a load.
 
Here is an interesting link.

http://www.nittotire.com/Content/pdf/Replacing%20Tires%20on%20Light%20Trucks%20-%20Technical%20Bulletin.pdf
 
Two ply(4ply rating) will I predict be a swaying, lane changing, unsafe truck/rv. Look for 27x8.50-14 They wont be in stock in most stores, but are not hard to order.
They are basic a 6ply LT tire the same height as a 205x75-14.
 
I know that a lot of tire places are going to a policy of putting only OEM size/rating tires on. Seems that if they put something else they can be sued in the event of a blowout causing an accident.

Rick
 
Higher ply tires usually gain extra carrying capacity by increasing air pressure. What are the recommended air pressures for your vehicle? How does that compare to the maximum air pressure of the car tires? I would not use the same size car tire if the recommended pressures for your vehicle are higher than the maximum pressure of the car tires.

The difference on six tires is about $400 total. If you plan to keep the motor home for more than two more years or 10,000 more miles, I"d go with the truck tires, just to have fewer things to worry about in the future. Car tires may not hurt resale value in a private sale because the buyer won"t know the difference. If you trade it in to a dealer, they will probably notice, but it may not matter to them either.

Dumb question: When (If?) dealers replace motorhome tires, do they put on truck tires or car tires. You could visit a dealer to ask, and also check what tires are on their used units, especially the units with new tires.
 
I bought some new car tires to use around the farm on small ATV trailers and such, on sale a while back. They are so soft and pliable you can't believe it. They work fine for what they are doing, but I would never put them on something big, heavy, and valuable like your camper.

Get the proper heavy duty tires.
 
From my camper experience, buy the best, heaviest tire you can afford. Also, if you inflate the tires at 50 psi or more, then invest in the high psi metal stem inflation valves.

That road surface can by 30 - 50 degrees hotter than the outside temp, so your tire tread surface is hot and under about 90% of maximum rated pressure.

Most car and pickup tires never operate even near that high % of there maximum pressure.
 
I don't know much about tires so can't advise you there.
I do hang out on the Airstream trailer forums and after seeing photos of the damage done by a blow out I know I wouldn't want to have one.
 
John.. One thing you can't deny... More plies are better.. I've got 10 ply on my M1031 pick-up.. It will haul anything I can fit in the bed..
 
Are you buying used tires? A lawn tire here is 50 bucks. The cheapest 14" tire here costs a 100 bucks or better. The 10 ply Michelins I put on my pickup with steel sidewalls were around 360 dollars each.
 
Local Walmart has brand new Goodyear or Douglas 195/75-14s for $52 each and an extra $12 for balancing and mounting. If I was home I'd use my own tire machine, but I'm not.
 
A little added info. I got around to finding the
DOT date codes on the tires on the RV now. The are only three digit. That means they were made before year 2000. DOT code is: JFJ280. That means made the 28th week of a year ending in "0". I assume 1990. So, they ar 24 years old! I doubt anyone makes a tire today that would last that long.

As to measurements in-between the duals. The OEM 185R-14 truck tires have 1 1/4" of air space between the sidewalls. If I used the 195/75-14 car tires - there will only be 3/4" of air space when properly inflated. Not sure if that is adequate or not.
 
You're only assuming 3/4" based off the nominal width of the tires. The actual width of the tire can vary quite a bit from brand to brand. It will probably be less because the car tires will squat more under the heavy RV.
 
New tires are built so cheaply especially car tires. It would not surprise me if the ones you have would out last the new ones.
I would be concerned with sway and wiggly feeling from the car tires.
 
No way will a new radial last as long as your tires have, but it's not unheard of for bias ply tires to last that long.

3/4" air space doesn't sound like much. Each tire will only be able to deflect 3/8" before they touch. Doesn't sound adequate but I don't know.
 
I went back and re-read the original post. Going by the GVWR and actual front and rear weight of the vehicle it sounds like the original tires were overkill. There has to be a reason why the manufacturer would use a tire that was way over rated (and much more expensive) for the application than simply going with a car tire with a sufficient weight rating.
the 185R-14C tires appear to be 8 ply or at least 8 ply rated.
They didn't need 8 ply tires for the load capacity so I'd have to think they used them for stability.
I did a google search of that size tire which lead to this site.....
http://www.tires-easy.com/cgi-bin/rshop.pl?dsco=135&cart_id=73536515.135.15425&sowigan=&Breite=185&Quer=&Felge=14&Speed=&kategorie=6&LoadRange=Load+Range+D&Marke=&ranzahl=4&s_p=&m_s=3&x_tyre_for=ALL&suchen=View+Tires
I have no first hand experience with them. Just thought you could use the info for comparison.
 
I've bought tires from Tires-Easy several times.
Many times their prices beat anybody - even with
the shipping charges. With this size - not the
case unless I buy their cheapest no-name tires
from China. With Chinese tires - it's a crap-
shoot. Some are fine and some are absolute
garbage. I bought brand new tires for my wife's
diesel Volkswagen for $27 each plus $10 shipping a
two years ago from Tires-Easy. Those tires are
Chinese and have been great! Not willing to try
with a heavier vehicle yet. Not with an unknown
Chinese brand.
 
I'm not a price shopper. I'm a value shopper. Sometimes the best value is the item with the lowest price, sometimes not.

Yokohama and Hankook have decent reputations. Never heard of the other brands in that link.

Have you posted about this on an RV forum? Maybe someone has first hand experience with passenger tires on a rig like yours.
 
Late reply but: I owned two of those little 1T Toyota chassis trucks. One with a little furniture box and one with a flat bed. Used P tires on both. No issues at all in 40some thousand miles. I wouldn't make that substitution on single wheels due to sidewall stiffness, but on duals, no problem with sway. And remember, this was a furniture box, and was driven in an area with a lot of cross winds.

The flat bed was loaded ( actually overloaded) a lot and never had any failures or poor handling. I was hauling fill material (rock crusher screenings) for a basement repair and on one load I weighed 10K lbs! Mistake loading and never did that again. But, no handling issues or tire failure.
 
May want to check into American made Coopers. I've used them on two different Suburbans and love them. They also come in P , C , D , E load ranges. I get the "C",s which are 6ply and aren't much more than P,s are but not as harsh riding as D or E. Just a thought. You don't have to jump all the way to D or E from P.
 
I have Coopers on two of my trucks. Cooper does not make the tire size I need though IF I get the LT tires. Only 6-8 companies in the world are making 185R-14C tires. Yokohama, Hankook,Kumho,Nexen, and a few Chinese brands. They were only used on Volkswagen bus camper vans, dual wheel Toyota motorhomes, and Toyota 1 ton box trucks with duallies like U-Haul used to use.
 
I just got done stripping a 87 Toytoa dually box truck. I knew the original owner. He used passenger car tires for all the time he owned it, but had to use one size smaller then called for due to sidewall clearance. He got away with it but did not care about he speedometer being off, nor did he use the truck fully loaded all the time (like an RV). The OEM tires are supposed to be 185R-14C with a 1874 lb. load rating and 25.6" diameter. The passenger tires thin enough to use as duals are the 185/75-14. they are only rated 1290 lbs. each and are 25" diameter. I have not been able to find a passenger tire the correct size with enough side-clearance. Walmart's catalog says to use the 195/75-14". It's looks to me though that Walmart is wrong. With any other company's catalog that do not carry the 185R tires, when I look up the tires . . they say "none available." I tried Cooper's master catalog and Michelin's.
 
I'm a member of several Toyota RV forums. The
problem is - most people on those forums know little
about mechanics, trucks, etc. Most (but not all) are
people who buy RVs, pay someone else to work on
them, etc. Not a lot of "hands on" people there
like there are on this tractor forum. And yeah, I'm
sure now I've insulted someone over at some RV
forum.
 
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