Matching Hard To Find Tires

[tireman9]

While there are many posts on the difficulty many are having finding the specific brand & size they want, shortages are not always limited to a single brand or a line or size.

Some general guidelines to keep in mind when shopping for other options.

You can mix brands on a vehicle. If doing this, you should still keep the sizes the same or very close to the original size and Load Range.

You should not mix tires on front axle. BOTH should be same tire.(i.e. brand or size or type or design or Load Range)

You should not mix tires in a pair of duals in addition to being the same brand or size or type or design and Load Range, you need to match the physical OD within 1/4". I have a couple of blog posts showing how to properly measure the OC to meet the measurement goal.

How to match duals

and

How to replace duals.

Mis-match size can result in a tire wearing out in a couple thousand miles or even a tire failure due to load imbalance.

While it is possible to have the left pair of duals a different brand or design than the right side duals this is not a desirable situation but some times there is no alternative.

[nitehawk]

I asked my Michelin/Hankook/many other brands tire dealer if a rumour I heard last week about ALL trailer tires now being made in China and his reply was a disgusted: YES!

[dickandlois]

While there are many posts on the difficulty many are having finding the specific brand & size they want, shortages are not always limited to a single brand or a line or size.

Some general guidelines to keep in mind when shopping for other options.

You can mix brands on a vehicle. If doing this, you should still keep the sizes the same or very close to the original size and Load Range.

You should not mix tires on front axle. BOTH should be same tire.(i.e. brand or size or type or design or Load Range)

You should not mix tires in a pair of duals in addition to being the same brand or size or type or design and Load Range, you need to match the physical OD within 1/4". I have a couple of blog posts showing how to properly measure the OC to meet the measurement goal.

How to match duals

and

How to replace duals.

Mis-match size can result in a tire wearing out in a couple thousand miles or even a tire failure due to load imbalance.

While it is possible to have the left pair of duals a different brand or design than the right side duals this is not a desirable situation but some times there is no alternative.

Question. You mention that the OD when matching tires - they should be with in1/4in. In your post, but mention a difference of 3/4in in your information link.

http://www.rvtiresafety.com/2013/12/how-to-match-dual-tires-when-replacing.html

When measuring a tire for dual matching it needs to be off the vehicle and fully inflated. If the tire is brand new you can expect even radial tires to see some size increase after a couple hundred miles so it is difficult to match new and used and get correct numbers.

The solution if you are replacing just one tire would be to confirm your front tires meet the 3/4" difference and then place a new tire on one front and the old tire on the other front position.

Meeting the 3/4" max difference is critical as ignoring this figure can result is a failure down the road even if the tire has been properly inflated.

Are you referring to the same requirement in the two locations or is there something different you are referring to ?

Rich.

[bm02tj]

I think one is OD and the other is circumference .25 inch X 3.14 = 0.79 3/4 is 0.75

[tireman9]

I think one is OD and the other is circumference .25 inch X 3.14 = 0.79 3/4 is 0.75

Correct. It is very difficult to accurately measure OD but OC is relatively easy.

You don't need to match front tires other than it is suggested they be marked as the same size, brand, Load Range and design, and inflated to the same PSI based on the heavier axle end.

Each pair of tires in "Dual" application in addition to being same marked size, brand, design, load range and inflation need to have their OC measures and confirmed to be +/- 3/4" OC of each other. Yes a brand new tire will grow a bit so if I had to match a new and warn pair I would want the new tire to be smaller and closer in size. Usually duals should be replaced as a "set" of two tires but this is not always possible if you aren't running a fleet of trucks.

[dickandlois]

TireMan, Just finished measuring the circumference of a New XRV tire and it was 116-7/8in. with 110lbs of air.

With a OD of 37.5 the circumference come out to 99.5in. with no air or a 15% increase in circumference.

sizable difference.

Rich.

[tireman9]

TireMan, Just finished measuring the circumference of a New XRV tire and it was 116-7/8in. with 110lbs of air.

With a OD of 37.5 the circumference come out to 99.5in. with no air or a 15% increase in circumference.

sizable difference.

Rich.

Yup, That's why you want to get the OC measurement with the tires inflated and when comparing tires be sure both have same psi.

Sorry if I wasn't completely clear in the above psots about measuring inflated tires. Sometimes I forget that others don't do things I consider "automatic". Down side of having a lot of experience.

[bm02tj]

And if you tell the complete whole story assuming people know nothing no one will read it .

So use the short version and people can ask questions they will learn more that way.

[dickandlois]

One more question regarding matching hard to find tires.

When you need to change one of the rear dual tires and replace it with one of the front ones, because it meets the 3/4in. requirement for the maximum difference in circumference, do you need to also consider the direction of rotation as a factor.

Kind of remember it as being an issue years ago and there is a set pattern when rotating tires on cares.

The inside and out side rims on the rear are placed back to back, rotated 180degs. changing there direction of spin relative to each other.

Rich

[wolfe10]

While there are a few (very few) directional tires in RV sizes, those are clearly marked with arrows on the sidewalls. For the rest, direction of rotation or change in direction of rotation is a non-issue.

Information to the contrary is basically a carry over from a LONG time ago.

[dickandlois]

Thanks Brett, Clears up one little loose end.

Rich.

[tireman9]

I asked my Michelin/Hankook/many other brands tire dealer if a rumour I heard last week about ALL trailer tires now being made in China and his reply was a disgusted: YES!

Skipped over this first time around. Not sure what you mean when you are talking about "trailer tires". While a majority of travel trailer tires of "ST" type come from China that is not 100% true. I understand one large mfg, Maxxis, is not made in China.

Now if you are talking large Truck/Bus radials i.e. 19.5 and larger rim then that claim is certainly not true. Many TBR tires are identified for their intended application. Some for fronts, some for drive, some for trailer and some "all position". I have not read about any general trend for TBR size "trailer" tires to be made in China. In fact I am pretty sure some are made in the US.

Note I do not have access to all production data and am not sure if I have ever seen tire type by country in a published manner.