M604 front tyre size

[Handclutch]

My 604 had 10/11.2 x 24 tyres fitted. They were an odd pair and made the tractor sit higher at the front than I thought it should. Before ordering new tyres recently I did several online searches and kept coming up with 9.5x24 as the correct size. I figured a previous owner had fitted the larger tyres because they would have been more readily available.

The tyre shop thought 9.5's were were wrong but I told them they were correct for the tractor. They do look slightly skinny for the rims which seem to be 9" (I didn't get to measure them with the tyres off) but are quite okay and appear similar to pictures of other 604s.

However, I now see in the operators manual that the tyre pressure chart references 11.2x24 as well as 9.5x24. There must have been two sizes available? Does anybody have any knowledge on this?

Appearance wise, I'm not concerned but will the smaller tyres effect the front wheel lead (the bigger ones would provide more)? The other question is whether MM provided different front axle drive ratios depending on wheel/tyre size? If they didn't there's no issue - either size should work. But if they did I probably should swap back to 11.2's.

Any insights would be greatly appreciated.

Jack

 

[molinegb]

Am sure ones have here are 11.2's. on 704. Have old set off a Massey 97. Are lower profile. Depends on company that made. Trying to find a fwa for a 604.

 

[SWMolines]

I believe they were on 9.5-24s originally.

 

[MMDEL]

Front and rear tires HAVE to match on a 4 wheel drive tractor depending on the gear ratio. other wise it will put a strain on the drive train and break something. Did the previous owner possibly put larger tires on the rear, thus the larger tires 0n the front???

 

[BMG1]

You need to know what transfer case ratio your tractor was built with. MMDEL is correct. If you have the wrong size for the gear ratio you're going to tear something up.

 

[molinegb]

704 has 12.4 . G706/97 9.5's Both 34 rears. One Elwood and other Coleman.

 

[Handclutch]

Thanks for all the responses. I have found the answer - it was sitting in my parts book all along.

Both 9.5s and 11.2s were available, each with their own transfer case ratio. The 9.5s had a 20 teeth pinion and a 48 teeth output gear while the 11.2s came with 19 and 49. I think it's almost certain that mine came with the bigger tyres but I can't be absolutely sure. I'll try to get the build card from the Floyd County Museum which should answer the question. Failing that, I might have to drop the transfer case and have a look.

In a previous life the tractor had been fitted with a very heavy front blade, so it is possible that bigger tyres were added. As I understand it, increasing the size is not the big problem - there is more 'lead' but the axle is still 'pulling' and doing what it should, albeit with a bit more wheel slip - but the other way around is bad news. No 'lead' and the drivetrain is going to bind up and something will break.

Again, thanks for all the help.

Jack

 

[Handclutch]

A follow-up to this earlier conversation. This week I received the build card from the Charles City Museum (mail to Australia has been very slow recently) but it really doesn’t tell me much at all. It shows 25 tractors serial numbers 51 to 74, all assembled on January 13. Mine was shipped on March 26. Several of the tractors have got ticks for options such as belt pulley, wheel weights, different rear wheels and Tel-O-Flo/3 point. However, mine only has a single tick under a column marked B/M 80-22. 80-22 is also the order number shown in a different column.

I’m guessing B/M must refer to a standard combination of features? Some other tractors also come under columns marked with B/M and an order number, again with no other options ticked off. Can anybody shed any light?

I had thought that each tractor would have its own detailed card but that was just an assumption on my part. Looks like I will have to find some way of counting the teeth on either the pinion or output gear to be absolutely sure of the correct tire size.

Jack

 

[BMG1]

A follow-up to this earlier conversation. This week I received the build card from the Charles City Museum (mail to Australia has been very slow recently) but it really doesn’t tell me much at all. It shows 25 tractors serial numbers 51 to 74, all assembled on January 13. Mine was shipped on March 26. Several of the tractors have got ticks for options such as belt pulley, wheel weights, different rear wheels and Tel-O-Flo/3 point. However, mine only has a single tick under a column marked B/M 80-22. 80-22 is also the order number shown in a different column.

I’m guessing B/M must refer to a standard combination of features? Some other tractors also come under columns marked with B/M and an order number, again with no other options ticked off. Can anybody shed any light?

I had thought that each tractor would have its own detailed card but that was just an assumption on my part. Looks like I will have to find some way of counting the teeth on either the pinion or output gear to be absolutely sure of the correct tire size.

Jack

Jack,
B/M stands for Bill of Material. These were basically special order units that could potentially have unique option content different from what was offered in the dealer order guides. I wish the B/M lists existed but so far they have not turned up so there's no way to tell how your tractor left the factory. "80" order numbers are typically export units with most shipping to Australia or surrounding areas. I think you're stuck with counting gear teeth in your transfer case and comparing that to what's listed in the parts book. You could try jacking it up and measuring the circumference of the rear wheel and compare to the amount of revolutions the front tire makes for one rear tire revolution. They should travel the similar distance if your tire size and ratios are correct. This isn't perfect since you're not measuring the tires under load which should be slightly less distance than the unloaded tire jacked up.

Brian

 

[molinegb]

None of the "new" tires match the old ones.

 

[Handclutch]

Brian

Thanks, that’s very helpful. There were eight tractors with ‘80’ – B/M order numbers in that batch. Six of them with the same order number were shipped on the same day, January 22. The other two with individual order numbers were shipped in February and March (mine).

I don’t know how many came to Australia. I’m told that there were three on display at the 1964 Melbourne Show (same as your State Fair) but I expect there would have been more than that. It seems mine is probably the only one to have survived - haven’t heard of any others in the 20 years I have owned it. I'll let you know how I get on.

Jack

 

[Handclutch]

I dropped the transfer case today and found I have the 19/49 pinion and output gear (in excellent condition). If my calculations are correct this ratio would drive the front wheels a little slower than the 20/48 combination. I’m now almost certain that the original 11.2s were the correct size.

Checking back to the parts book I notice that the tire sizes all have a (R-1) or (R-2) next to them. Does this refer to rim sizes? I can’t think of any other explanation. It says that 18.4- 34 (R-1) rear tires and 9.5-24 (R-1) fronts can be used with either ratio but 18.4-34 (R-2) rears and 11.2-24 (R-2) fronts require the 19/49 ratio.

By the way the information is provided in the parts book, if the tractor was originally fitted with 9.5s it would have had the 20/48 ratio. The 19/49 combination appears to be an option.

Any thoughts or suggestions appreciated as always.

Jack

 

[molinegb]

We used a fwa 97 Massey for year back in 70's with 9.5. and 34's. Was mainly used in field. Never gave any trouble except splitting rims. On hard pack road fwa had to be disengaged. If you didn't could feel drive train "wind up" and front wheels would hop trying to catch up.

 

[BMG1]

I dropped the transfer case today and found I have the 19/49 pinion and output gear (in excellent condition). If my calculations are correct this ratio would drive the front wheels a little slower than the 20/48 combination. I’m now almost certain that the original 11.2s were the correct size.

Checking back to the parts book I notice that the tire sizes all have a (R-1) or (R-2) next to them. Does this refer to rim sizes? I can’t think of any other explanation. It says that 18.4- 34 (R-1) rear tires and 9.5-24 (R-1) fronts can be used with either ratio but 18.4-34 (R-2) rears and 11.2-24 (R-2) fronts require the 19/49 ratio.

By the way the information is provided in the parts book, if the tractor was originally fitted with 9.5s it would have had the 20/48 ratio. The 19/49 combination appears to be an option.

Any thoughts or suggestions appreciated as always.View attachment 117238

Jack

R-1 is standard ag tread pattern and dimensions. R-2 is Rice and Cane deep tread pattern which were generally a taller tire for the same published size. What size rear tire do you have?

 

[Handclutch]

Thanks for all the assistance. I have 18.4 x 34(R1) on the rears. Looking at the parts book again it seems that this combination of 18.4 x 34 and 9.5 x 24 can be used with either ratio. Given the information about B/M referring to a special combination, I suspect the Australian importer would have specified larger front tires – the 11.2s were correct after all. It was fairly common at that time for imported tractors to be fitted with up-spec’d tires.

There was a photo of a 604 on Facebook a couple weeks ago with what were clearly 9.5s on fairly wide rims. But yesterday, quite by chance, I found photos of a propane 604 that I photographed in Wisconsin about 10 years ago and it was fitted with 11.2s. Wish I had remembered that earlier.

To keep the tractor completely original I think 11.2 would be the go, but at this stage I’ll stick with the 9.5s (unless anybody in Australia wants a couple of brand-new 9.5 x 24s). It’s been an interesting exercise and part of the fun of working with these old machines.

Jack