Getting tires for the '97

[sgtsandman]

Stock tire pressure for mine was 35. I used the information off the side wall to figure out what Ford expected the tire to support and ran the numbers off the 31” tires to get as close to the same number but not below. That gave me 36 psi.

I’ve never had problems with that pressure but I have a fiberglass cap, a wooden platform in the bed, and a bunch of miscellaneous recovery and repair equipment. So, I’m running heavier than a Ranger with nothing in the bed.

Also, with these tires, they will tell you if you have too much pressure in the tires. Your truck will handle like the steering is loose and tend to wander about the road.

Run the math but I’ve found the psi for the new tires to be pretty close to the OEM tire. I still run the math just to be sure.

 

[James Morse]

I finally got the tires on so it's back to oem configuration. Totally changed the truck for the better. To me it almost looks raised but it's not. Rear diff clearance 8-3/4", front diff 7-3/4". Door sill plate is at 21-1/2" so that's quite a step. It probably raised it a good 1-1/2" anyway which doesn't sound like much but I really see it compared to before.
I haven't had a chance to drive on them yet.

Even though technically it's not raised, there's a 3" steel block in there. The blue tape is 3" long. If I set it next to the '99 rwd it's quite a bit higher.

 

[James Morse]

Add to that 31x10.5R15s are a pretty large tire for Ranger

I'm not sure why you say that, because the way it came from the factory was 265/75R15 and if you compare that to a 31x10.5-15 you'll see the 31" are very slightly larger and I mean slightly. It probably would have come with a less agressive A/T tread but that's the oem size for the truck.
There is a lot less selection in 265's.
It can vary depending on the exact kind of tires but I think you'll find if you compare similar tires of the same tread/type, the differences between the sizes is negligible.
When I'm out I'll check the speedo vs gps. It was reading significantly high with the smaller tires.
I agree it's the largest tire they ever put on a Ranger in '97. If you got a basic rwd you could get like 195's so a lot of difference. The Mazda runs 235's, if I tried to put the 31" tires on it I am guessing there would be fitment problems.

 

[James Morse]

As to the pressure if oem was 30psi and I'm running oem size tires then as suggested 30 front and 28 rear is probably pretty good. Yes if I load it up maybe I want to bump up pressure a little or some kinds of off-road I might want to go 25 or even 20 I suppose.

Thanks for the tests about that.

 

[James Morse]

Here's the deal on tire sizes. 4x4 in '97 could come with 215's (standard) or 235's (comes with either preferred equipment package) or 265's (optional).
4x4 XLT got the "payload package" as standard. I don't know what that is, maybe a bit heavier springs in back.

 

[James Morse]

Toyo makes a tire in both 265 and 31" - Section witch and tread with is .1" bigger for 31". Diameter is the same. That's why I don't see them as significantly bigger. Anyway, that's the info I had when I went thru all this. So the truck should be setting at the same height it did oem. I don't expect any issues from the 31" good lord I hope not!

 

[sgtsandman]

As to the pressure if oem was 30psi and I'm running oem size tires then as suggested 30 front and 28 rear is probably pretty good. Yes if I load it up maybe I want to bump up pressure a little or some kinds of off-road I might want to go 25 or even 20 I suppose.

Thanks for the tests about that.

I would keep an eye on tire wear and maybe get a tread depth gauge. The gauge is cheap and will show if there is accelerated wear in the tread anywhere faster than a calibrated eyeball. They will probably wear fine with the pressures you are using but better safe than sorry.

Also, each tire is different and can wear differently. My winter tires on the 2019 had accelerated wear on the inside of the tread and I couldn't keep an eye on it since the girlfriend was running it ragged and putting it away wet. The "All Terrain" tires it came with have been wearing just fine. Go figure. When I have the money to put another set of tires on it, I'm going to have them check the alignment. It's too late for these tires since getting any alignment correction now could potentially get thrown right back out.

 

[ericbphoto]

I would keep an eye on tire wear and maybe get a tread depth gauge. The gauge is cheap and will show if there is accelerated wear in the tread anywhere faster than a calibrated eyeball. They will probably wear fine with the pressures you are using but better safe than sorry.

Also, each tire is different and can wear differently. My winter tires on the 2019 had accelerated wear on the inside of the tread and I couldn't keep an eye on it since the girlfriend was running it ragged and putting it away wet. The "All Terrain" tires it came with have been wearing just fine. Go figure. When I have the money to put another set of tires on it, I'm going to have them check the alignment. It's too late for these tires since getting any alignment correction now could potentially get thrown right back out.

Rotate them often to help even out the wear. I try to rotate tires at each oil change and immediately after an alignment. I leave them where they are for the alignment so the tech can see what's happening. Then rotate afterwards to even out the wear.

 

[sgtsandman]

Rotate them often to help even out the wear. I try to rotate tires at each oil change and immediately after an alignment. I leave them where they are for the alignment so the tech can see what's happening. Then rotate afterwards to even out the wear.

The wear is too far gone and questionable for another winter season. It would be better to leave the all seasons on it for the winter and look to save up money for another set next year. If they handle well, I'll get a set of mud tires for the steel rims and run the OEM tires for the winter until it's time to replace them. I'll spring for a set of winter tires on the clown car instead. They are half the cost of winter tires for the 2019 or 2011 and I can afford to let her burn those much easier than on one of the trucks.

 

[James Morse]

What they ended up doing was putting the weights on the rim of the inside of the wheel. They recommended putting the ones with the least weights on front, not sure why, but I did that. So left front, 1.5 oz, right front 2.0 oz, left rear 2.5 oz, right rear 5.0 oz all of it in the same place (!). I don't know at all what those weights look like compared to good/bad but there they are I'm a little concerned about the 5 oz. but like I say I'm ignorant what that represents except it's out of line with the others.
After all the talk about putting stick-on weights inside the wheel so make them close to the outside of the wheel (like normally done), they said they didn't want to do that because they could come off and it would cause a bad problem if you were going 70 on the freeway. As you can see there are no weights on the outside of the rims which is what I wanted (for cosmetics) now if they actually are balanced good that will be great.
I don't know enough about it to figure if changing a weight's position side to side across a wheel makes a difference, seems like it only would if the out-of-balance was skewed one side or the other. Frankly in all the times I've gotten tires for cars I just went and got them and never looked at them past that. Like, I never knew they had date codes.
I set them 30 all around to start. I have the tool box and a bunch of stuff in it, so I'd be a little over empty in the back (ok, tool box isn't totally back, but anyway).
I'm going to do the water test. Can you describe chalk test?
I'll check gps speedo vs dash, it should be good now. And see how they feel.
Yes I have the depth gauge for the tread. It might be a while before I see any change because I don't put many miles.
I didn't have alignment checked. The old tires were wearing pretty evenly and it drove good before with the old ones.
The place I went was kind of weird in that I got different answers not only from different people but from the same person even. But they got the tires in fast, they were new, and they did the weights like I asked and the price was ok (competitive relative to me ordering them from Tire Rack then taking them to be mounted).
@don4331 I didn't mean to be argumentative I guess I thought you were saying the tire size was too big but I guess you're just saying that's the biggest tire you can put on a Ranger without mods and I agree. I'm not sure if the 3" blocks in the back were stock with 4x4 or if they put a little extra there when the 265's were optioned (according to Oasis - since I don't have a door sticker, but I trust Oasis). Section with increase of .1" means .05" (about a mm) bigger per side so I doubt very much there would be rub problems in front but I'll check that too.
Anyway this morning they don't look so huge to me as at first but I still think it sets pretty high compared to a lot of vehicles and I'd say has as much clearance as just about any stock vehicle designed for possible off road use.
Sorry for going on about it, but it was a big deal, been talking about it for a year now. Tires of course are not symmetrical, if you look at the side tread it's opposite side to side just like a lot of wheels are. Which I don't really like, did a lot of searches about that and am/was at the point of it-doesn't-matter and not losing any sleep over it. If it impacted performance I think we'd hear about it. If I wasn't clear about that, what I mean is if you look at some wheels they have the spokes slanted; one side will slant forwards, the other side backwards. I just don't care for it.
I do like the blackwall showing vs showy white letters but nothing against people who like them that way. Garage smells strongly of new tires this morning.
Thanks for all the help.

 

[James Morse]

So, first drive, checked speedo vs gps, reads 35 going 34, reads 45 going 44.5, reads 55, going 55, reads 60, going 60. So not reading high any more and not reading low which you wouldn't want. I found best way to get a reading is a nice level stretch of road then set the speed control, it keeps it even.
To me that confirms, that's what the truck came with as to tire size. Before it was reading 5 to 6 mph high with the 235's.
Not noisy, maybe can hear a little bit but you'd have to try.
Didn't feel any vibration up to 60, sometime I'll try at 70 and normally I'd never even get to 70 although I know if I ever went around Atlanta they drive 85 or used to anyways.
I'm going to put some water on my driveway and go thru it and check for consistent tread contact.
I was next to a newer (current gen I'd say) Ranger Lariat Supercab at a light and it looked to be the same height maybe very slightly lower. For what that's worth, nothing I guess.
Looking at it in the parking lot there's a lot of daylight underneath. It's definitely higher than it was, noticeably.
So like people said when I was originally scoping out what truck to get, that one out of the box is already pretty capable for light to moderate off road. Also in that '97 you were getting skid plates which later you had to option or get FX model.
So now I got to knock out getting the vents higher. Then that'll be all I want to do right now to it - oem size tire, manual hubs (done), and raised vents.
I realize skid plates are added protection but if you're hitting skid plates it kinda means you have an issue so it's nice to know they are there but not like one intends to then try them.

 

[James Morse]

I'm wondering about what you mean by

Run the math

What maths are you running?
The tires say 50 psi max cold to support 2270 lbs. But that's max I'd never run that it's just the tire's spec.
I have the tread depth gauge. It'll be a while before I get any useful information there because I drive so little.
My good pressure gauge lost the little insert that seals it against the stem so I went and got another at Auto Zone it's crappy. I mean, maybe it's kind of ok, but the indicator just comes out like 1/2" for the 30 lb range and my old one comes out like a couple inches or something to me the latter is easier to read and just seems like it'd be more accurate. Made a tiny leather washer and fixed the old one, gonna return the crappy one. I used to like having a couple -good- ones then I'd check them against each other to make sure there's no huge discrepancy.
Water test for tread contact seemed ok but pretty easy to check again.
Of course the pressures we're talking about are cold psi but depending on the kind of driving and the climate there's some things to consider. If it's 0F or 95F out that's going to change what "cold" means so typically there's some adjustment needed for seasons - depending.
The other thing is after driving on them they warm up so you can't drive, come in with them hot, then measure psi and expect it to be the same as cold, but I think it might be useful information. As an example, and I know it's a completely different situation, but in the Fiesta on the track my memory says the interest really was in psi hot so desired psi cold depended on what psi you got hot after some track laps because that's the psi you actually were using them at.
Not to overcomplicate it... just saying.
Most of my driving is going to be in town then on the highway it's probably never over 65mph. If I'm on the highway (55, or 65 on the interstate) I'm probably on my way to off-roading. So no really high speed driving at all. So I think what I want, assuming no air-down, is the minimum psi I can use, keeping in mind that if I read things right under is worse than over.
Anyway after all that, right now I set them 31psi all around cold at ambient say 70F. I don't think I'll be far wrong, might go a little lower in the rear if I'm not loading it up.
If the truck sits in the sun one side will get pretty warm/hot the other side not and that can change things.
Probably it comes down to the feel, the wear, the contact patch, is it loaded, all that.
I think I'm probably boring the heck out of people with this.

 

[James Morse]

This one gives consistent results I think it's accurate. The other ones generally read the same but I don't get consistent readings or they don't agree.
It's kind of neat it has a button you can release air. It holds the reading. Vicky picked it up at Goodwill a while back but I hadn't tried it and it seems good.
I set 32 front 31 rear, going with that for now, if it's not ideal I don't think it's far from it, might go a little lower/higher depends how it feels/wear/contact patch - usual stuff.

 

[sgtsandman]

I'm wondering about what you mean by

What maths are you running?
The tires say 50 psi max cold to support 2270 lbs. But that's max I'd never run that it's just the tire's spec.
I have the tread depth gauge. It'll be a while before I get any useful information there because I drive so little.
My good pressure gauge lost the little insert that seals it against the stem so I went and got another at Auto Zone it's crappy. I mean, maybe it's kind of ok, but the indicator just comes out like 1/2" for the 30 lb range and my old one comes out like a couple inches or something to me the latter is easier to read and just seems like it'd be more accurate. Made a tiny leather washer and fixed the old one, gonna return the crappy one. I used to like having a couple -good- ones then I'd check them against each other to make sure there's no huge discrepancy.
Water test for tread contact seemed ok but pretty easy to check again.
Of course the pressures we're talking about are cold psi but depending on the kind of driving and the climate there's some things to consider. If it's 0F or 95F out that's going to change what "cold" means so typically there's some adjustment needed for seasons - depending.
The other thing is after driving on them they warm up so you can't drive, come in with them hot, then measure psi and expect it to be the same as cold, but I think it might be useful information. As an example, and I know it's a completely different situation, but in the Fiesta on the track my memory says the interest really was in psi hot so desired psi cold depended on what psi you got hot after some track laps because that's the psi you actually were using them at.
Not to overcomplicate it... just saying.
Most of my driving is going to be in town then on the highway it's probably never over 65mph. If I'm on the highway (55, or 65 on the interstate) I'm probably on my way to off-roading. So no really high speed driving at all. So I think what I want, assuming no air-down, is the minimum psi I can use, keeping in mind that if I read things right under is worse than over.
Anyway after all that, right now I set them 31psi all around cold at ambient say 70F. I don't think I'll be far wrong, might go a little lower in the rear if I'm not loading it up.
If the truck sits in the sun one side will get pretty warm/hot the other side not and that can change things.
Probably it comes down to the feel, the wear, the contact patch, is it loaded, all that.
I think I'm probably boring the heck out of people with this.

To figure what psi the new tire should be at, you first take the maximum pressure and maximum load of the original tire and divide the load by the psi. That gives you the amount of weight the tire supports at one psi. Multiply that by the the psi on the door jam sticker. That gives you the load the vehicle manufacturer expected the tire to support.

Then take the maximum load of the new tire and divide it by the maximum psi on the side wall. Take that number and multiply it by various inflation pressures you want to try until you at least meet the load the vehicle manufacture wanted to support. If you can’t hit that number , err on the high side.

That is why I’m running 36 psi with the KO2s instead of 35. 35 psi was not enough and 36 psi is too high but it’s better to be high than low.

 

[James Morse]

Thanks sgt. Here's the thing I have no door sticker. Oasis says it was built with 265/75R15's. Gross is 4920 (just throwing that in).
Can Oasis have errors, yeah, because it says deep-dish aluminum wheels (it has) of size 6"x14" which obviously is wrong.
Tire pressure is something not on Oasis.
---What would be super useful was if someone had this same truck and oem 265/75R15's, what's their psi say on the sticker??

If you compare Cooper 235/75R15's (that would be your tire with preferred options, and 265's were optional) to K02 31x10.5-15's, the max load and max psi are identical. So the desired psi to match mfg would be identical. My '99 (not 4wd) has the sticker, 225/70R15's were stock with psi at 30. If you do that comparison it says K02's should be at 26.5 which is, I think, ridiculous. Likewise if you assume sticker psi was 35 it would indicate 43 for the K02's also ridiculous. It makes me doubt that you will see a sticker with a 35 psi but who knows.

If you compare Cooper 265/75R15's to the K02's, the 265's have a higher load rating. If I assume sticker psi of 30, it would indicate the 31" tire should be at 37 - pretty close to what you use. I think it's high though.

It's highly dependent on the numbers used of course so if any are not right it skews things. To really know you'd have to know the exact tire on the original not just the size.

It seemed to me that when I aired down just a bit from like 34 to 32, the truck feels better (better steering feel). If it still looks like a decent contact patch (water test) then I'd be tempted to stay there. But you say underinflated is worse than overinflated, why is that??

I carry a 12V inflator (and a searchlight) in the cavity under the left pull-down rear seat, there's a lot of room in there. The other side has the jack.

I like your way to looking at it. I'm not sure it gave me a definitive answer but between contact patch tests and the way it feels, and wear, when that happens. Right now my gut says 30 is too low and 37 is maybe what you want in a fully loaded maxed out truck but for everyday use I am tentatively sticking with the 32-34 psi range unless something pushes me to change that. I think at 35 it feels like it kind of wanders and at 32 more secure feel. For what that's worth. I could certainly be wrong.... but I think not horribly wrong.

THANKS.