Tire help

[bikerdib]

No I didn't measure the rolling circumference, I thought it would be subject to too much variance (knowing exactly when I made a complete revolution).

After I already changed the tires, I thought about it, I could have made a mark on the tires using a level then going one revolution to that point again but it's too late now. I really don't feel like dis-mounting the Carlisle, re-mounting the Firestone, then probably again dis-mounting the Firestone and re-mounting the Carlisle.

Doing a little math, it looks like the Carlisle will be about 0.4 to 0.5 inch shorter rolling circumference than the Firestone.

Like I said in my previous post, I think more difference can be had by say replacing worn fronts with new tires while not replacing worn rears (I'm referring to same size old and new). This would especially be true if you had R1s front and rear and replaced worn fronts but not the worn rears (and I have seen people do that).

 

[/pine]

FWIW...
I got this from another forum in regard to replacing 21 x8.00 -10 tires

Glad to have dropped in tonight and hopefully save you some grief & aggravation.The Carlisle 20x800-10 will not match the rolling circumference needed.Been there done that paid the price!...

 

[bikerdib]

But I think he was talking about a different tire in 20X8-10, I used a 20x10-10 All Trail that has a mounted diameter of 20.1 inches compared to 20.5 for the Firestone Field & Turf. However, if you look at my report you will see there is even less difference in the static load radius when the tire is supporting the tractor; only 1/8 to 3/16 inch difference. A few psi under inflation of the Firestone can make that much difference in static load radius since they seem to have a lot of sidewall flex.

There is also this option if you don't mind loosing some traction:

Look at product 511116
Carlisle Tire & Wheel Company

They have a mounted diameter of 20.8 so all you would have to do is lower the inflation slightly and you'd probably have the same rolling circumference as the Firestone.

 

[/pine]

They have a mounted diameter of 20.8 so all you would have to do is lower the inflation slightly and you'd probably have the same rolling circumference as the Firestone.

this is the same justification (to use the Carlisle tires) buy the OP on the other forum when advised that the r.c. was not the same...

if you look at my report you will see there is even less difference in the static load radius when the tire is supporting the tractor; only 1/8 to 3/16 inch difference. A few psi under inflation of the Firestone can make that much difference in static load radius since they seem to have a lot of sidewall flex.

There is also this option if you don't mind loosing some traction:

Traction is not my real concern...
To prevent damage to the drive train...my understanding is that there is really only one significant measurement and that is the rolling circumference...

 

[bikerdib]

this is the same justification (to use the Carlisle tires) buy the OP on the other forum when advised that the r.c. was not the same...


Traction is not my real concern...
To prevent damage to the drive train...my understanding is that there is really only one significant measurement and that is the rolling circumference...

And that's my point, the rolling circumference can be directly affected by the static load radius of a tire. Rolling circumference is related to the mounted outside diameter of a tire as well as that tire's static load radius. If you use the original tire but only run say 10 to 15 psi, the static load radius will be smaller (and therefore the rolling circumference is smaller) compared to the original tire running 25 to 30 psi. Vice versa, if you have a tire with a slightly smaller mounted diameter but one that has a static load radius that is very close in size to the original tire then the rolling circumference is likewise close to being the same as the original. Remember, the outside diameter of a circle (or in our case the rolling diameter) is pie times the radius (in our case the static load radius) times 2.

I know the All Trail is not an ideal replacement (that would be the no longer made Firestone Field & Turf) but it was the closest I could find with a traction type tread.

The mounted diameter of tires from different manufacturers can vary for the exact same given size and in fact it can even vary between different lines of tire from the same manufacturer.

Take for instance the All Trail I used in 20X10-10, it has a mounted diameter of 20.1. While the tire I gave a link for, the Turf Saver in 20X10-10 has a mounted diameter of 20.8. Same manufacturer, same given size but with a different mounted diameter and possible different static load radius and rolling circumference.

That's why I'd like to see manufacturers give the static load radius of tires. Then we could compare directly to see if a tire will suite our needs.

 

[/pine]

That's why I'd like to see manufacturers give the static load radius of tires. Then we could compare directly to see if a tire will suite our needs.

Again...I have seen no mention of "static load radius" (other than in your posts) in regard to the proper rolling circumference....IMO "fiddling" with tire pressure is not the answer to prevent damage to the 4x4 drive train...all the techincal data I have read states that it is paramount to maintain the correct rolling circumference...nothing else...

If you feel comforatable with what you have...that's fine...but until I can find the correct combination I will continue to seek other options...I can't see taking the risk of damaging the gear train for the sake of tires...

 

[bikerdib]

You are missing the point of my explanation of the static load radius. If you know the static load radius, you can do some simple math to find the rolling circumference of any tire. Most likely, that is the way manufacturers find the rolling circumference, they know the static load radius and do the simple math to get the rolling circumference. You think they mount each tire type and roll it along the floor under load?

I know you don't see mention of static load radius on most manufacturers websites; you also don't see mention of rolling circumference on their websites.

Firestone is one of the few that give good info on their tires, such as here:

http://www.firestoneag.com/tirelist_pop.asp?ref=168&load=0

 

[bikerdib]

BTW, I wasn't trying to promote using inflation to adjust rolling circumference. I was pointing out that inflation pressure will affect the rolling circumference of any tire; even the original tire used from the factory.

I'm also not trying to talk you into anything. If you find a direct replacement tire that gives the exact rolling circumference of the original tire, please let me know.

 

[/pine]

You are missing the point of my explanation of the static load radius. If you know the static load radius, you can do some simple math to find the rolling circumference of any tire. Most likely, that is the way manufacturers find the rolling circumference, they know the static load radius and do the simple math to get the rolling circumference. You think they mount each tire type and roll it along the floor under load?

I know you don't see mention of static load radius on most manufacturers websites; you also don't see mention of rolling circumference on their websites.

Firestone is one of the few that give good info on their tires, such as here:

http://www.firestoneag.com/tirelist_pop.asp?ref=168&load=0

As for a "static load"...is that before or after an FEL is added?...and every different attachment connected to the back of the tractor is going to change the load on the front wheels...so are you suggesting changing the tire pressure every time a different implement is attached? or adjusting the pressure for different loads in the FEL?

I got your point...but my point is...someone (quoted from another forum) that used the same tires you have "paid the price"...to me, they are not worth taking the risk especially if you can't run at recommended pressures...

sorry I just don't accept your speculations based on everything I have read about the problems finding replacement tires of that size...you could be 100% correct but IMO with so many people with the same issue i just think there would be more factual data to support the use of those (Carlisle) tires and there isn't...

 

[/pine]

If you find a direct replacement tire that gives the exact rolling circumference of the original tire, please let me know

ditto...

...to date the only absolute way to remedy the problem is to replace both front and rear wheels and tires...which is what I am considering...