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psi in triples

3K views 6 replies 3 participants last post by  Cherze 
#1 ·
20.8 triples.. what tire pressures should I run..
Axel mount... thinking 19-18-15... but not sure.
 
#2 · (Edited)
will depend on horsepower and and ground speed and if it is towed or 3pt. i'll do some guessing but can redo this if you need. jd 8850 370 hp at 5mph should weigh total of 40000 to 42000lbs. towed implement rear axle weight should be 18000 to 20000 front 21000 to 22000 depending on total weight 55% front 45% rear. for triples multiply axle load by 0.4 and use a single tire load chart. rear tires20.8x38 radial 7 psi bias 12psi is minimum 20.8x42 radial 6 psi bias minimum 12psi. front20.8x38 8.0 psi 20.8x42 8.5psi calculations based on 22000 rear and 26000 front. if you have fluid it should be split equal between all tires on the axle. forgot to mention if on steep side hill you should be 4psi higher to compinsate for lateral weight transfer.

had to fix some calculations on this. should not try to talk to kids while doing calculation. had my initial weight to high.
 
#3 ·
Sorry.. triples in a mfwd..

Maybe 38000 lbs total.. when fully loaded.. saddle tanks on planter tractor can hold up to 12k.. when planting no draw bar weight to count.. transport is when there will be more weight on the Axel.

Guessing at it because I don't want to have to much weight that far out, and for turning etc. I was told yesterday I could almost go to 5? That concern was if you run over a rock.
Radial duals and an older dual before tires were changed so its pretty wore.
 
#4 ·
what the hp and ground speed just for info. 38 or 42 never heard of triples all around on a mfwd or just the rear. ballasting is done for field conditions. roading is total out there. is the 38000 including the 12000 of the saddle tanks or not. i may have to just send you a chart and you may have to scale your unit to get this right. also need front tire size.
 
#6 ·
you are very heavy for that horsepower so your front to rear balance may be way off.. what i would do is scale the front and rear axles of your tractor with your implement in field and transport position. then find your tire size on this chart, find the weight and get the correct psi. if your road weight is a lot higher that field you will probably need to set the tires for that. http://www.firestoneag.com/webres/File/Inflation-Tables/TireInfo-LoadInflation-A.pdf or Tire Pressure hope this helps you out since you are that heavy and i don't know the front to rear balance i know i would be weigh out. so the best would be to scale the tractor to get it right.
 
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