The Stovebolt Site Forums The Parking Lot Big Bolts Metric Tire size

I finally found 22.5 in rims for my ‘52 6400. Does anyone know what the metrics tire size should be? I believe the 8” wide is what fits in American specs.

Multiply the tread width in inches by 25.4 to get the equivalent size in millimeters. An 8" wide tread footprint would convert to a bit over 200 MM.
Jerry

If your 22.5" rim center hole is larger than original you'll need to make a sleeve to reduce the hole size...your '52 would have a 4.75" hole originally and the smallest 22.5 is center hole 5.25", but it could be larger.

Mike B

A 255 80R22.5 tire would be similar to a n 8.25x20 in diameter but it will be wider and could cause clearance problems on the tie rods. A 9R22.5 is just about a direct replacement for an 8.25x20. A 235 80R22.5 is about the smallest you can get in a 22.5, but it will be smaller in diameter than an 8.25x20 and will cut down your speed. I don't recommend the metric low profile tires on an old vehicle. The tried and proven 9R22.5 and 10R22.5 tires they came with 60 years ago seem to work better. Trying to convert inches to mm in tires will really not produce any available tire sizes.

I am using 10R/22.5 duals on the drives and 235/80/22.5 on the steers, these are all mounted on the original 6" 22.5 Budd 6 lug wheels on my '57 5700 LCF.

The 22.5" wheel that fits a 52 6400 is only 5.25" wide, unless you've found a wheel I'm not familiar with.
The narrow rim width is your limiting factor on picking tire size.
As crenwelge explains, 9R22.5 is the size you'd like to run.
If you look up specs for a 9R22.5 tire they will list a recommended or allowable rim width, 6" or one size wider. I haven't looked up similar metric 22.5 tires but doubt any with a suitable overall diameter fit anything narrower than 6", if even recommended for a 6" rim.

Back to the 9R22.5
You have 5.25" rim, 9R22.5 tire needs a 6" rim by the book, you can actually fit it on a 5.25" rim, it will work, it's not technically recommended, but you don't really have any other options. I've run this combo with good results thus far.
Those 22.5x5.25" rims used 8x22.5 and 7x22.5 tires which I believe have been gone and obsolete for many decades.

So are you saying that unless the rims are 6” wide or less, they WO t work on my truck? I’m supposed to get them tomorrow and would hate to end up with 10 rims I can’t use.

What did the new rims come off of?

Mike B

I don’t know, I’ll have to ask. Right now they have 295/75 tires that are mostly bad.

I was trying to say I'm unaware of a 22.5" wheel with 10 lug on 7.25" bolt circle made in any width other than 5.25" wide. I was assuming, probably incorrectly, that if you were buying 22.5" wheels for a 52 6400 those are the wheels you found.
Ideally that wheel would come 6" wide, but I've never seen or heard of that.

Any wheel that fits a 295/75R22.5 tire is more like 8.25" wide.
What they came from, or the bolt pattern is very relevant. At this point I'm not seeing how they'll be useful to you, the tires or the 22.5" wheels you have found.

Thanks, I’m glad I didn’t buy wheels I can’t use. I guess I’ll have to stick with 19.5”. Maybe this is why so few big bolts get back on the road.

Depending on how many miles you want to put on it, and even that's a small consideration, you can certainly run multi piece wheels and 20" tires as original, nothing really wrong with them.
More info here
https://www.stovebolt.com/techtips/wheels/

I don’t know enough about them to find some that will work. I’ve heard that after they are worn a certain amount they are wont to come apart.

So I am not sure I am following everything. Am I correct that you have found some wheels that you think will fit your vehicle, but they now have 295/75R22.5 junk tires on them? If so, it is very common for people to mount 295/75/R22.5 on stuff like farm trucks because they are so plentiful. I am in the trucking business and I can't give them away. I have to pay disposal fee. They will fit , but they are certainly not recommended. 295/75R22.5 should have a rim 8.25" wide. If you have found 22.5 some wheels to fit your vehicle, A 19.5 tire will be much smaller diameter than wheat cam new on your truck. I would buy them. They are very scarce. Throw away the junk 295/75R22.5 and buy some 9 R22.35 or 10 R22.5. The 7x22.5 and 8x22.5 tires became obsolete 50 years ago. And 9x225 and 10x22.5 is what everyone used and had no problems.

Just make sure the bolt pattern is 10 on 7.25”, not 10 on 8.75”!

Ed

I was told those tires would be on rims that are at least 8” wide and I shouldn’t use rims wider than 6”. Also that 10/22.5 tires are too wide also.

The Firestone 10R 22.5 that I had mounted on my 6" wheels look fine, not deformed, the duals have plenty of space between them so they won't kiss, the shop that mounted them said they will be ok on those wheels, it sure makes a world of difference on the way it rides.

10X22.5 tires will run right along side of a 9x20 tube required tire which was a very common tire for your size truck back in its day. And it will work just fine. Whoever is telling you stuff i reading thing out of a book and never experienced it in real life. However, asE as EdPruss stated make sure they are10 on 7.25 bolt circle. If they are 10 on 8.75 they are worth srap iron price and the disposal fee of the tire will be more than the worth of the wheel. Whoever is blowing smoke up your chimney about the width may be doing the ame thing about the bolt cirfle