Gear ratios for tyre options

JR.

Member
Location
Ip21
Hello all. I am trying to work out my options for tyre pairings on my T7210 AC. With the JD tractors the book gives you a calculation to work out what wheel pairings you can have and what the tolerance with rolling circumference variation is, because obviously not all tyres have the same RC but there is only so far you can push it.
I can't find this for my NH, Does don't seem to be able to provide me with anything and neither have NH yet, despite a direct approach.

Anyone else got any ideas?
 

Flat 10

Member
Location
Fen Edge
JD do seem fussy. How about you look up the rolling circumferences and work out ratios of your current set (if you know they were on from new) and make sure new ones are the same? I am staggered how much the ratios between front and rears can vary (same nominal sizes obviously) between brands.
 

Matt L

Member
Trade
Location
Suffolk
Most manufactures can supply a booklet with they tyres in to work out the ratios.
Just ask your dealer what the lead ratio should be.
DONT just change brand but same size as previous as they may actually have a different rc and end up outside the recommended lead ratio.
 

C.J

Member
Location
South Devon
What size and brand did it come with ?

What rim sizes do you have ?

What do you want to change to ? - wider/narrower,taller/lower.
 

JR.

Member
Location
Ip21
The JD system - once in a spreadsheet works ok. I can’t find the same for NH. I have worked out the RC for current tyres but was surprised at variation between brands so there must be some tolerance. That with having newer wheels on the front or back could also throw things out. So it’s the tolerance I need to work out what I can pair.

I have 650/65r42 rear and 540/65r30 front Michelin’ Omnibib or mulitbib. I want to go wider and higher spec on the front only to avoid having to dual up front. Rear axle dualled with 650’s but damage already done with fronts.

Thank god for the Terry Elsey team who pointed out that I had been advised to buy the wrong set of wheels by Fieldens.
 

Against_the_grain

Member
Arable Farmer
Location
S.E
I swear our machines start to experience ratio issues once the tyres get worn. Its like an unlocking/bang when you take your foot of the brakes.
 

JR.

Member
Location
Ip21
That’s the size I was looking at - the 600. Fieldens told me I could run 710/55r30 and I had them on order when they went pop. Thankful Phil at TE put me straight.

There must be some tolerance because the RC of a tyre will vary so much in its life. Very often fronts wear faster than tears so is there a point at which the issue to replace tyres is not about lack of tread/grip but distortion of the ratio.
 

Matt L

Member
Trade
Location
Suffolk
I swear our machines start to experience ratio issues once the tyres get worn. Its like an unlocking/bang when you take your foot of the brakes.
Yes it is possible as there is a large circumference difference between new tread and bald tread. The lead amount should be between 1 and 5 % to enable the proper function of the 4wd system, I have seen tractors with new tyres fitted on only one axle causing massive transmission wind up on braking. Turns out it was running around 9%. He had been driving it for weeks before thinking it was the tyres
 

Could a ‘Meat Tax’ be on the cards in the UK?

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Written by Richard Halleron from Agriland

The latest machination coming from the so-called ‘opinion formers’, who seem to have the ear of government advisors in London, is the introduction of a ‘Meat Tax’ at consumer level.

This approach, it is argued, would have the combined impact of reducing meat consumption levels (I can really see the health benefits coming through now), while also helping to reduce the overall carbon footprint of production agriculture.

What absolute drivel! In my opinion, none of this makes sense at any level. This is a scurrilous and unfounded attack on livestock farming in this part of the world.

Yet, it has to be taken seriously. I make this point because economists at Rothamsted Research have already crunched the numbers where the introduction of a ‘UK...
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