LT tire vs "P" tire..

[diesel4me]

Came across two 245/75-16's that were brand new spares,under pickups and never were taken down..rims are JUNK though,completely rotted,the whole center of one rim was missing--I will try to get a picture of it,if it doesn't crumble to rot flakes when the tire machine breaks the beads..but that's another topic..

Question I have is one tire is a Firestone "LT" load range E .
The other is a B.F.Goodrich ,thats a "P" (passenger) rated,cant see a load range letter,I'm assuming its "B"..this tire naturally has a lower load rating,but is still plenty sufficient for my truck's needs..

Now I know the LT tire will either have more plys or thicker ones that the "P" tire,I'm just wondering if I pair these two up on the same axle,if they will fight each other or make no real difference (as I've noted in the past when I had "E" range tires in the rear and "C" rated ones up front--I saw no disturbing handling issues at all)--but I had pairs of each on each axle,not one LT and one P rated tire..

I can have these tires for free,and they still look new,not all dry rotted,they still have nubs on them..and are equal in diameter,the treads are almost identical too..

My thoughts is my 3 ton ingot wont handle any worse than it ever did,but I would like to know if anyone else has run an LT and P rated tire on the same axle and had any issues before I go thru a ton of work dismounting tires ,etc..
If I had too,I do have another "P" rated tire the same size,but its about half worn,I'd rather use the ones with like new tread ,especially in winter..

 

[obijuank5]

Unloaded you will be fine. It's the loaded characteristics that will hurt you.
Make sure the tires are not too old to use. They may look new but the actual composition of the rubber ages and deteriorates.
Also with age tires get hard which I would assume would be a strong negative in cold weather performance.

 

[diesel4me]

I rarely carry anything,maybe a 500 lb tractor or firewood once in a blue moon..the plow up front is the heaviest thing it carries--for that reason I plan to keep the load range E tires up front..
I dont carry much in the bed--its getting so punky in the wood floor I had to lay steel plates over the wood so stuff wont fall thru!..

These tires look practically new still,even have the blue stuff on the white letters,and aren't petrified,they are still soft,and I could only pump one up to 20 psi,the rim I mentioned was like a pile of rust nuggets that sat on the ocean floor 30 years,you have to see it to believe it.

I feared it would explode the rim if I put any more air in it!..I know you cant see how cracked they may be without inflating them first,but they looked good at 20 psi..mostly they are just dirty from road splash..(maybe road salt pickled them !)..

But the tires seemed to been protected from UV rays under the truck beds,they survived quite well..I didn't get the date codes yet,but I am not scared to run them--I've had worse on the truck before,that were losing nuggets they were so cracked,but they were 8 ply E range ..

Age does matter I know,but I've used a lot of old tires as long as the rubber looked ok and weren't stiff as hell or dry rotted with no issues..
I also dont go 75 mph or long distances with this truck on interstates..

One thing that kind of puzzles me,is I've owned K10's and K1500's that only had P rated "car" tires ,like 235/75-15's and those trucks were not that much lighter than the 3/4 tons,and I plowed with a heavy ingot Fisher plow weighing like 500+ lbs ,never had a blowout or any issues with them being overloaded..the front springs rode dead against the bump stops with the blade on too!..

So maybe I'm over worried about this--if those 15" tires withstood the load,I doubt these will have any problem..only thing I'm fearing is it might "pull" to one side with one P and one LT..but I have probably done just that unwittingly in the past and never noticed anything ..

 

[HankScorpio]

"P" rated tires are for cars in my opinion. My wifes GMC safari had "P" rated goodyears when it showed up and they were awful. A GMC safari is not a heavy van, it's a mid size, but the tires were maxed out. Even at 40-50 psi they were bulged on the sides. When you drove it always felt like it was swaying, like the shocks were shot. It wasn't the shocks, it was the tires flexing. I put a full set of "LT" on it and all the ride issues were gone. No sway, handled and felt way better. Throw that "P" away, its not for a truck. I understand you are trying to keep things cheap but tires are the only part of the truck that touches the road, the only part that actually gets the job done. You already know that a 10 year old tire is considered too old by date code. Check your codes, if the rim is toast I am sure the tires are too. I have also run tires that are too old and showing cracks and been OK, doesn't mean it was a good idea. Don't you have to pass safety inspection in MA? Tires are part of that inspection too.

 

[diesel4me]

Yes,they do inspections here...you should see the tires they passed that were on it up until a few weeks ago--not horrible,but less than 1/4 tread left,some checking on the sidewalls,and a few had more than one plug in them--one front one has two in the same puncture that was very close to the sidewall--that one held air fine though!..they were goodyear wranglers ,and I'll have to see if they were P rated or LT's,I cant recall..

I'm being "cheap" because I need to get a roof on this house,before any more interior damage gets done..this truck has multiple other issues,and once its past winter,it will likely be off the road ,possibly for good,just use it as a yard/plow truck,or if I am able too,yank the engine out and put a gas one back in it,and put new inner fenders,fenders,maybe a whole nose on it,the inner fenders are practically non existant,and they wont pass it for a sticker when its due in june in its present condition--or shouldn't,anyway..
So whatever tires go on it wont see many miles or high speeds...I'm unable to buy new ones for a truck thats going to just sit a lot..

 

[Blue85]

I think putting together a set of tires from spares is an interesting project. Seems like they deploy 10's of thousands of the same tire and they never see the road. For a lot of years GM would use 16" steel spares under everything, while most got 17" or 18" alloys on the truck, so they were never rotated in. Just get 2 more like you have - or find somebody to trade with?

I once bought from 3 different people and got a matching set of almost new Sumitomos...

 

[JoshHefnerX]

With the different load ratings between the P and LT tires you're gonna have to do some math to get the pressures right, one will be noticeably bulged and much softer than the other. Use the load rating index and a little math to figure out how much load you have on that tire and adjust accordingly. Wouldn't surprise me if it ends up w/ a bit of a pull to one side or the other.

 

[TerryD]

I wouldn't try to run them away the same time if you can help it. Keep the P as a spare. My K2500 is wearing P 265/75s due to current budget constraints (bought used to pass inspection last year) and man are they spongy. The size overall height difference between them and a LT in the same size would probably be over an inch. Even at 45psi they look flat...

 

[diesel4me]

I looked at the tires I had up front on the truck the past 2-3 years and they were only "P" rated 255/70-16's I got off a friend when he decided to get 4 new tires,they still had about 1/4 tread left, and no uneven wear..
They were a sawtooth summer type tread,but they did well plowing--I've had nearly bald tires up front before and this truck seems not to care,it rarely spins the tires or gets stuck,its such a heavy beast..

They had some tire plugs in them though,but they never gave any grief until a month ago,one plug got dried out and it let the tire leak down very slow,I had to pump it up weekly..never went below 20 psi..
I was putting 55 psi in all 4 tires too,those front ones said on the sidewall that was the maximum pressure rating..
I dont recall the load rating ,but I'm guessing each tire was rated for at least 2000 lbs..

I noticed the truck rode much smoother with the "P" rated tires up front..rears,I try to keep LT tires with an "E" rating on that end of the truck,they resist punctures and will bear up to any load I happen to carry,which is rare..they also dont let the tail end wag side to side like the flabbier P rated sidewalls would--up front it doesn't seem to do that with them up front for whatever reason..

The P rated tire in question has a load rating in excess of 2600 lbs,I think that is plenty not to have any worries about overloading,its the softer sidewall and tread plies that may create a handling issue,being paired with an LT on the other side of the same axle....
I guess the only way to know is to try it and see..


I happen to have 4 decent B.F. Goodrich T/A radials ,245/75-17" "E" load rating.
A friend gave them to me ,and I didn't look close at them,when I got home I discovered they were 17",not 16's..

Too bad no 17" rim I have seen in salvage yards have the right offset to work on a square body..and I'm balking at spending money on rims,or trying wheel spacers,etc,when I could use that money to just buy the right 16" tires..

I am going to try listing them for sale or trade,see if I can get a matching set of 4 16" tires in exchange..
I asked around at a few tire shops that sell used tires,but they were not interested in trading,just selling--they'ed be happy to take them for free though..
I'd give them to another needy person first!..

I'm on the hunt for some more spare steel 16" GM rims,the 8 lug ones are getting harder to find locally now,many of them,including a few of the 7 I currently have,are getting pretty rusted and flaky on the inside of the beads and the inside facing portion..still useable,but probably not for much longer..

I have a set of 4 rims 16" off a 1990 Ford 3/4 ton I've used on the past 2 plow trucks that are nearly identical to the GM ones,even has the right stamping so the stock hub caps fit..those are in the best shape out of all of them,so I'm going to run those on whatever tires I end up putting on the truck..they are a tiny bit narrower than GM ones but they dont rub the calipers or tie rods..

You guys wouldn't believe how many never used spare tires there are still under truck beds in the salvage yards here..I don't know why they dont harvest them right away when the trucks come in on a ramp truck or get picked up with the loader..seems a sin to see so many never used tires go to waste,and many are less than 10 years old,

It only takes 5 years or so before some trucks undersides rot away to nothing around here--I'm hoping I can get a photo of that rim posted that rotted so bad the whole center dissapeared !..it may just crumble when my friend goes to break the beads on the tire machine though..
I've seen rims at the dumps metal pile so badly rotted I cant believe they didn't fail on someones truck too..

 

[JoshHefnerX]

16 is turning into a dead size, you may be better served for the future going to 17.

 

[diesel4me]

If I could buy four 17" rims off some other truck that would actually work without hitting the calipers or tie rod ends ,that don't cost as much as 4 new 16" tires,I would..but nothing I've seen so far fits that bill.(and the 17" tires I have probably wont last more than a year or so,they aren't exactly deep tread,so I'd be in the same boat again)..

I'm not rich enough to buy 17" H2 rims and have them hogged out to fit over the hubs--junkyards here want at least $75 each for them,in scuffed up but useable condition..

There are still plenty of 16" tires available both new and used,though I admit they aren't as popular as in the past..it's the 16.5's that are extinct and very costly if you must have that size (I know those suck,I'd never buy 16.5's !)..

 

[JoshHefnerX]

Brand new 17" steelies can be had for under 100 ea. I imagine c-list would have them substantially cheaper if you kept an eye out. It may not be the cheapest thing to do now, but if you plan to keep the truck it may be worth it down the road.

https://www.summitracing.com/parts/pcw-51-7981/overview/ is an example 17x9 8 on 6.5. 4.25" bs should clear. Believe those are the same size I got on mine (but my memory isn't what it used to be).

I have/had a couple of cars on 16's and the sizes have gotten really limited. Getting ready to buy some new wheels for one of my vehicles due to that problem. I imagine trucks are the same way - if not soon..

 

[Blue85]

16 is turning into a dead size, you may be better served for the future going to 17.

No, PYO's forever!



But really, how many sets of tires will you buy for one vehicle? A less popular size will make your search longer and may cost a bit more, but I don't think new wheels will save money. If decent used tires will go 35,000 miles, a new set of steel wheels will likely be rusted out before they pay themselves off.

There are so many mounted sets of wheels & tires changing hands out there that unless you're dedicated to a certain wheel style there are lots of options. This is much cheaper than buying wheels, buying tires and paying for mount and balance. Along those lines, it doesn't pay to go too cheap on used tires because that mount & balance money (usually $80+ per set) could have gone towards newer tires to begin with.

 

[diesel4me]

What sucks is there are tons of 17" rims for newer IFS trucks that had the same 8 lug ,6.5" pattern,but the offset is way wrong due to the IFS..if they hadn't made the rims with so much negative offset I'd be able to run those without issue..but they don't want you to be able too,that would be too easy..
I'm not about to spend $500+ bucks on just rims when the truck isn't worth that much WITH the new rims & tires!..were talking an old rotted out plow truck,not a decent truck actually worth a few grand..

Last saturday when I was at my friends shop,some guy pulled up to my truck in the parking lot,he had a square body about the same year as mine,same color,only a fleetside version..he stared at it several minutes,backs up,pulls around to the other side,and gawked some more--my friends said "Hey,he must want to buy it Bob!"..
At this point,after the 6.2 still pissing me off with fuel issues and me starting to hate diesels in general,I was hoping he'd get out and make an offer on it..but he drove away..dammit!...

I'd sell him my diesel Suburban too,if he'd been interested..package deal!..then I'd probably go buy a gas powered farm tractor with a loader,or a backhoe with a cab to plow my yard instead..no plates..no insurance..no inspections..and I really could use a loader,I'm getting so I cant lift a dam thing now..

 

[JoshHefnerX]

eel wheels will likely be rusted out before they pay themselves off.

You guys keep mentioning this 'rust' stuff.. not familiar with it.

 

[imiceman44]

With the different load ratings between the P and LT tires you're gonna have to do some math to get the pressures right, one will be noticeably bulged and much softer than the other. Use the load rating index and a little math to figure out how much load you have on that tire and adjust accordingly. Wouldn't surprise me if it ends up w/ a bit of a pull to one side or the other.

That's what I was going to say but read first to see if someone got it first .
Bob for what you use the truck for and you put them on the rear you will be fine.
Check the maximum weight rating and psi on each and let me know I will tell you what pressure to run in each.
People run the small donuts on the back all the time and car companies are comfortable with it.
Just don't use in the front

 

[diesel4me]

Now THIS is what I call "rotted out rims".....

Unfortunately everything here looks like this after a few years,thanks to road salt and general high humidity much of the year..

Imagine if you had a flat,and this was the spare ,that lived under the truck bed for a decade,when you went to put it on!..

The tires are still soft and supple as new though..no dry rot ,cracks,or weathering at all!...
I used my manual bead breaker to break the beads yesterday at my friends shop,he said his tire machine's bead breaker is messed up and doesn't want to work half the time,and figured the rim would just fly apart if he could get it to work!..
I didn't have to push very hard on the handle to break the beads..

 

[JoshHefnerX]

Holy crap dude.

 

[diesel4me]

Well,I picked the tires up from my friends shop yesterday..

As I was looking them over,I noticed the "P" rated B.F. Goodrich one had a "This Side Out" message molded into the rubber...and..it was facing the inside of the rim....

I pointed that out to my friend ,and he was like ..."Sorry,I didn't think to look at that,never even noticed it!--I know you usually like running the blackwalls facing out,so I mounted both that way.."

He was not having a good day--had a Honda CRV on his lift,was doing a 4 wheel brake job,and one rear caliper he ordered from NAPA up the road was the wrong one..and now the car would be stuck on the lift till he can get the right one..(guy looked up a Honda Pilot at NAPA!..)--he made it to the store to return it just as they were locking up too,and a hassle ensued,they did not have the correct caliper,and he said the guy who looked it up wrong will likely be canned because it was one of several mistakes he'd made yesterday..

I didn't want to ask him to take the tire back off and flip it around,it was all balanced,and he was not in a good mood,I am lucky he mounted both tires for free as a favor,didn't want to piss him off..

He said in his 20+ years of tire shop experience he has never seen or heard of a tire failing due to being on "backwards",this tire isn't "directional",it is "asymmetrical",which means one side has a slightly different tread pattern than the other..supposedly it channels water away to the outside better and provides better traction in wet weather..

Did some online searches and the general consensus is the worst it might do is tend to make the tire more likely to hydroplane,it wont make it fail structurally --so I said screw it--the truck will likely never know the difference with it in the rear,and I'm not brave enough to trust it at highway speeds anyways,especially in crappy weather..

I put both on the truck today ,I put the "P" rated tire on the drivers side,and the "LT" on the passenger side,because I have a small HF crane on that side and figured it would be better off there..

Had to use my HF "Earthquake" air impact to get the lug nuts off,my "Buffalo" old one wasn't gutsy enough..

Another stupid screw up on my part,was not trying the 8 lug rim off these tires that was still good enough to use on my yard trailer,to make sure the lug pattern was the same..I had already put both tires on,before I remembered I wanted to do that....and I should have had my friend mount one of the old tires on that rim too,so I wont have to try doing it by hand..

I've felt like walking death the past few days,so my mind isn't exactly sharp..thought I was having a heart attack by the time I got this done and put all the tools away,now my back is killing me--feel like I belong in a hospital,last night I woke up with a severe sore throat,but by morning it was almost gone......but my heart pounds like a pile driver after doing the least little thing--I'm probably going to be in line for a by-pass or stents I fear,and back surgery ..

I'm not going to worry about the tires--these are the "best" this truck has ever had on it since I owned it,they have never touched tar before,and have no cracking ,they didn't need much weight to balance them either...they will likely outlast it..

After looking at the undercarriage of the truck while the tires were off,I was disgusted to see both rear spring hangers on the drivers side have rotted thru in spots..they aren't going to pop off tomorrow or anything--but they will need some beefing up with angle iron eventually..another nail in its coffin...

First photo is the "P" rated tire..

 

[diesel4me]

Bottom photo is a duplicate..cant seem to edit it out..