Tires ag to turf conversion

[landman]

Ive got an older jd 870 with ag tires, the only option with this tractor. I need to replace the tires, weather cracked, and rims are leaking around the valve stem from whatever they put for ballast in the rims, think it was calcium chloride/water, too old for rim guard. So the ags are a real beast on my dirt driveway and chew up the woods trails, forget about getting it on the lawn. I want Turf tires, so I can get in the woods without a mess, and use chains for the winter. Is there some magic conversion guide so that I can keep the ratio for 4wd. The tires are 5.0-15 on front 11.2-24 on rear, is there a turf tire that matches this ratio combo, or should I shop for r4 instead?

 

[AKfish]

I'd imagine that your 870 would be close in dimensions to the 3000 economy series machines (3005 or maybe the 3032). Check the available tire sizes offered for those tractors.

Sounds like your rims will likely need replacement as well. Calcium chloride is some corrosive stuff!! 'Course if you go with turfs - you've got to get new rims!

There's a number of old posts on this forum regarding the calculations to match front tires and rear tires and ensure the correct differential "over-run" with 4x4. IIRC - it's just less than 6%.

That said, if you go with a new replacement set of matched tires and rims from a similar JD model - you won't have to worry about tire/differential overrun.

AKfish

 

[diesel466]

The john deere parts site lists turf tires and wheels for a 870. Sizes are listed.

 

[landman]

Thanks much, yeah this whole thing is gonna run me some big bucks.....

 

[Zebrafive]

Just because turfs were offered does not mean you can just put them on. As you mentioned you have the front to rear ratios to worry about.

You might check on JDParts and see if different ratios were offfered for the axles (there may even be foot notes saying what ratios were used with what tires). If the axles only have one ratio, do some searching and see if there are any gear pairs in the front axle drive train. Might be easiest to just ask the Service manager at the dealer.

You could find the loaded radius ratio of your tires and calculate the ratio and then make sure the turfs will have a similar ratio.

The fronts should run 1-5% faster than the rears.