Technical radial tires similar size as 11.00-15?

Are there any radial tires out there that are a similar size as the 11.00-15 bias ply dirt track tires? This is for street daily driving, not drag racing.



Ever since I got my 33, I've been wanting wider tires on the rear. I'd like 11-12" of tread width and about 30-31" or so diameter.

After looking around, I decided on the newer Coker/Firestone bias ply DirtTrack tires, as they are just about the exact size that I want. They arrived, I put them on a set of 15x10 "smoothie" wheels, and I absolutely love the size.

I had 25psi in them for the first day, but it felt like it was to much pressure, so I lowered it to 20 and it seemed to ride a bit better. I thought everything was great, however over night they have developed a flat spot so bad that this morning I don't feel comfortable driving faster than 25mph, I can see my radiator bouncing left and right, and I don't feel comfortable driving it like this.

As much as I love the look of these tires, and I want to run them (they were not cheap!!) I need something that I can drive to work in the mornings, I'd like to find a radial tire. I've had bias ply tires before and didn't mind them, but they didn't seem to flat spot like this. Probably because they had more plys, they were off-road jeep tires.

 

No really good solution if you keep the tires. You could jack up the rear axle every night and keep the weight off them, but what do you do while at work? Or air them way up so it removes the sidewall flex, air down in the morning....but again, what about during the day? As I recall, it was the tire carcass cord that was better or worse for this characteristic...nylon cord being the worst and rayon was better.....

Nope, looks like it will take a different tire construction.....as you have already concluded.

The high performance tires for OT Super Cars can supply the width and get close on the diameter, but not at 15" rim size. Think 19"/20"/21".....but no flat spots.......

Maybe 'Sport Truck' radials would have something that covers the range you are after. But they will be heavy too and the weight of tires and wheels in the sizes needed don't do anything positive for unsprung/sprung weight ratio. My signature line kinda covers these matters.

Ray

 

Yea, I definitely need something that can be used as a daily driver. I don't mind monitoring my tire pressure, but I don't want to have to change it (or put the vehicle on jack stands!) every time I park it for more than a few hours.

 

Heat em up in the driveway?
I had a old truck I put bias ply tires on, every morning on the way to work I had to drive about 1 mile to get them warmed up and round again. I was retreading tires at that time, I made the tires for myself.
Was a old 66 datsun pickup and I lived 20 miles from work. Drove the truck for a couple years with no tire issues. Was just the initial morning drive to get to the highway, by then they were fine.

Seems like 20 psi really is not enough air for the tires, if they create this severe of a flat spot.
Just a guess, but they may fail prematurely from being under inflated, if you run them at 20 psi.

 

Hoosiers

 

Thanks! For some reason Hoosier tires didn't come up in the searches I was doing. Must not have been searching very well, haha!

Looks like they have a 31x12.5x15 "Pro Street" radial that measures about 10.5" wide on the tread, and about 13.5 on the overall width and 31" tall. That's only slightly narrower than what the dirt track tires are, but I'd be fine with that. The dirt track tires are rubbing every so slightly on the side of the bed when the suspension flexes up. I think I'll go for those unless there's more options to weigh.

What size is that you have on your car? What pressure do you run them at? Do they ride good enough for daily driver? I'm used to a rough ride, my vehicles are jeeps and trucks, but that flat spotting I can't deal with, haha!

 

Those were what I helped by pal in Bakersfield spec out many years ago so I'm not sure on the actual tire dimensions, I do know the wheels were 15x10", at the time there wasn't much else available, this was prior to Coker doing the big dirt trackers.
They were one size smaller than their largest, not sure about the "pro street" thing.

 

I've been looking on the Hoosier website, and they say that all of their DOT tires technically pass the specifications for street use, but should NOT be used on public roads and highways. With the exception of the Pro Street tire. Looks like the Pro Street tire is the one that I want, it's pretty close to the size I want.

 

I run light truck tires on my daily driver. 31" dia, 10" tread, affordable great for the street, good look.

 

20PSI is too low for bias ply tires, you need a minimum of 28 PSI. Unless you have already damaged them because of too low of pressure, I suspect most of your flat spotting will go away. Gene

 

Flat spots overnight on Nylon or Rayon tires was standard procedure back when we all had bias tires. Usually it went away as soon as they warmed up.
If you don't like the ride with the tires you have at what should be the correct pressure for that tire you sure won't like the ride on a light truck tire with six or more ply rating though.

 

I respectfully disagree. Correct tire pressure for a given tire size is dependent on the tire loading. Probably difficult to find now for bias ply tires, but manufacturers publish tire inflation charts to match pressure with load. The variance is quite wide.

Ray

 

willys36, what brand of "light truck" tire are you running?

- EM

 

I contacted Coker, they said they suggest 32psi for my vehicle. Man, that seems like alot, as they rode kinda stiff even at 25psi. But I'll give it a try. I do like the look of these tires, I'd like to make them work!

But if they are too rough riding at 32 psi, I'll switch them out for the Hoosier radials.

Am I expecting too much from the tires as far as ride quality? I'm used to jeeps, with big puffy tires. They actually ride quite nice, but even on my lighter weight 46, I don't run anywhere near 32 psi with 33" tall tires, I run 22. But they are radials. For Jeeps, I usually use less pressure the taller&wider the tire is. But again, I'm not really used to bias ply tires. I did have bias ply tires on my 46 originally, but they were 28" tires, and I honestly can't remember what pressure I kept them at.

 

If the ride is rough with the tires properly inflated, the issue is probably not the tires. Maybe your shocks are too stiff, or your springs too strong for the weight involved.
My coupe is riding pretty rough these days, but my shocks are wore out. I suspect the installation of new shocks this winter will improve my ride quality. Gene

 

The truck does ride better (on the current much narrower radial tires) when I have weight in the bed, but that's not unexpected though. I was doing some runs to a storage unit this weekend, one trip I had probably 600+ pounds in the bed (a disassembled wood lathe, router table, welder, and a few other miscellaneous items) and the ride quality was noticeably better. But I knew that would be the case.

Even without the extra weight, the narrower radials (at 25psi) ride better than the wide bias plys at 25psi. At 32psi on the bias plys (I just air them up farther) they feel rock hard, I can't imagine the ride is going to be very good. Even at street pressure on my jeeps (25psi on my 4500lb TJ), I can push on the tire with my thumb and feel some give. And I usually run my tires until there's almost no tread left, and I've never had bad tread wear.

Could this ride quality issue possibly be due to the fact that I have radials on the front, and bias ply (with the Coker Dirt Track) tires on the rear? My gut tells me that this can't have any affect on the ride quality especially at low speeds, the warning on the tire of not mixing radial with bias ply must be for traction differences between front and rear, not ride quality. Or maybe not?

I'll give them an honest try at "correct" pressure before I ditch them for radials though. Would putting a bead of grease in between the individual leaf springs do anything other than make a mess? And what shocks would be good to look at for such a light weight rear? I'll measure the shocks that are currently on there, and see if there are any markings on them.

The shocks (and springs?) don't have many miles on them, I picked up the truck with only 4,000 miles on it after a home-garage restoration/rebuild, and most components on it were new, but it has put those 4,000 miles on since early 2000, so it's not really been driven hardly at all in the past 15+ years. In the past month since I've owned it, I've already put on an additional 2,000 miles, haha

I honestly will very rarely have weight in the bed, I normally would haul things in my F250, but it's almost full a with load going to the dump right now, so I did some small trips with the 33. And besides, I like driving the 33 better

Sorry for the long post, guess I'm just in a mood to type And I know I'm asking alot of questions, I mostly drive higher heavier 4x4 vehicles, the 33 Chevy is new territory for me

 

You have multiple issues going on here. The square inches of the tire interior volume versus the load being carried by the tire requires the psi be adjusted to be correct for the load being carried and allowing the tire to perform as designed.

I think the Coker employee who told you to use 32 psi either was just 'solving' your flat spotting problem.....or doesn't know squat about how tires function. The fact is, your are using a tire that was not designed for the application for which it is being used.....because you like it's appearance. That's okay as long as you understand compromises are part of the deal. Possibly the Hoosier tires will be more flexible without flat spotting, but the other issues remain.

Further, the larger tire is heavier than what you were using previously, increasing the unsprung weight enough to affect the ride, even if the pressure was correct for the load. Combining those two factors cannot help but adversely affect the ride. Add the possibility that your spring rates may not be ideal (maybe they are) and things just keeping stacking up.

Again, choosing the looks of components in spite of their unsuitability is common in out hobby. I do it, we all do it. It does require recognizing the laws of physics will have their way and means we must either find ways to minimize the adverse effects or learn to live with them, or both.

One last thing......running radials and bias ply tires on a vehicle at the same time can introduce some very unstable handling issues due to the sidewall flexibility differences between the two types of tire construction.

Ray

 

Picked up a set of the Hoosier ProStreet Radials, 31x12.5x15 I like them!

They ride quite well (I'm at 20psi right now, their maximum is 25), and are noticeably quieter at highway speeds too. I may try lowering the pressure a pound at a time over the next week, but honestly they are riding pretty good.

Hopefully the tread doesn't have TOO short of a life, but I guess time will tell

 

I have been running them for 25 years or so. Just went to the tire store and got tires that look good. They say Radial Belted as the brand name. Chinese maybe? 31x10.50R15 size. They still look new and have outlived probably 4 sets of front tires. I imagine there are several brands of that size tire out there that would serve as well as daily driver hot rod tires. Then if you are bucks-up, get a second set of rear mags and mount the sexy but problem prone pie-crust slicks for rod run night at Sonic drive in.

 

I concur with Willys36. Have Michelin 31X10.5X15's on the rear of my ride (8" wide wheels). Run 24 PSI in them and am very happy with the look and ride. Go to the Tire Rack web site and enter in the size of tire you are looking for and you will come up with 3 or 4 pages of choices complete with good photos of the tire and all relevant specs and dimensions on each. Great way to compare different tire sizes.
























8" wide wheel). Very happy with the look and ride with 24 PSI in them. Go to the TireRack web site, enter in the tire size you are looking for, and you will come up with 3 or 4 pages of choices with good photos of each tire and all the critical dimensions.

 

There are a lot of high boys out here running 31-32" LT's. the diameter look fits the body/fender lines. I see them every Saturday morning at Donut Derelicts..

 

Thanks willys36. I was just curious what they are given that I'm running a tire somewhat close in size to yours (285-70-15). It's always nice to have options. I'm also aware of the similar-sized Michelin.

- EM