I ordered a set of Mclaren solid tires for my 310SL. When they arrived they looked rather small so I got out the measuring tape. The Diameter was approx 6" smaller than my original tires. I ended up taking to their tech support they reassured me that they sell this size to everyone with 12.5-80/18. Reason being that air tires squat more that solid when you apply a load. 6" is to much difference for me, and I feel like it would put to much stress on the drive train. so I'm sending them back and getting a bigger size that is around 2" in diameter smaller that the air tires. What are your thoughts?
Your thinking makes a lot more sense to me.
While I can agree that the semi-solid tires might not squat as much as the pneumatics six inches sounds a bit much. Guess it also would depend on how hard a surface you worked on and how much of the time you are traveling with a full load in the bucket.
This is easy to check. Raise the bucket on the hoe to create it's normal load situation. Measure the diameter of the front tire horizontally. Measure the diameter of the front tire vertically. These measurements tell you the "squat" of your air tire with an empty bucket. If you want to check loaded "squat" repeat the above procedure with a bucket full of material.
Be sure to report on how they work for you, I have been curious about those.
bigger is better but I think the wheels should be larger or the same. ... The front tires typically travel more than the rear tires. The mis-match will keep the driveline in a bind. It will be difficult to disengage the fronts unless there is a clutch or differential between the front & rear. (which I didn't see in the parts breakout)
My thinking on the subject is it really doesn't matter how much they squat.... what matters is the circumference around the tire.... and I don't believe that changes when squatting
It's a 4x4 backhoe so any driveline wind up will tend to be normal just turning the steering wheel. I don't see that as an issue. I do see that the differential between the rolling speed front to back will be changed. I don't have anyway of measuring but think the front tires would tend to spin or skip whenever the load on one tire or the other was reduced just slightly causing accelerated wear.
You do pose a very good point. Wonder if you are right. If you are I think mclaren needs some better tech support.
The circumference is important the differentials are geared for the size of tires that came on your machine.
Yeah, when you said their tech support said it would work I was really wondering what kind of tech support they have there... I,m thinking they maybe misunderstood...about the front to rear difference in size.... the main thing I see those on around here is skidsteers with all fours the same.
I agree the circumference is what controls the "gear ratio" of the tire and that is obviously a huge difference of a tire of that magnitude. If you are only changing the fronts and not the rears to match, I would not change circumference at all. Obviously if what they say is true it would not matter on a Bobcat or whatever but on this tractor, big problem.
The rolling circumference is what matters here. There may or may not be a section in the user manual about tire selection. If they set TLB's like tractors there is a 3-5% overdrive on the front axle.
Is there a center differential on this 310SL ? If not, I believe the tires will scrub between the front and rear tires and stress the driveline for no productive reason... especially on pavement.
My Brother used to own a NH 155TLB I believe. It had the same size tires front/rear. I was very impressed with how it could nose down into a ditch, pick up a bucket full of material and back out. As to driveline bind, that's eliminated in gear ratios. There's no bind. Regardless of tire height.
Actually that's not correct. The important distance is measured from the center of the axle shaft to the ground. More squat, less squat, changes this measurement. In the process changes the gear ratio.
Yep. The overdrive is so the machine will actually turn a corner when in 4wd versus just trying to push the front end. In the tractor world this is talked about in terms of "pull" or "push". Pull meaning the front tires are slightly spinning trying to go at a faster ground speed than the rears when going straight forward. Push meaning the front tires are slightly scooting trying to go at a slower ground speed than the rears when going straight forward. In the pictures above this machine will lose this overdrive. It will actually have underdrive. It will scoot the front tires when driving in a straight line. The rears will push the fronts at a faster ground speed than they want. In the picture the difference looks to be overbearing and could cause premature mechanical failure. But again, this needs to be measured using the methods I described earlier.
I disagree. I say it is the circumference that matters. Think of the outside of the tire as a belt or Cat track that does not change much, just changes shape a little bit I would not stake my life on this statement with a solid tire, though. If we are having this disagreement, I would say to the OP that he should load up a bucket full of rocks on the existing tires and chalk the front tire and see if one rotation (in 2wd to eliminate scrubbing variable) equals one circumference on the ground. Then try the same with the proposed new size of tire both loaded down squashed and light, maybe with the backhoe sticking out to take more weight off and see if there is a difference. Inquiring minds want to know.
There's no driveline bind with OEM tires if the designers know their business. BUT, this is not about OEM tires. The OP is putting smaller diameter/circumference tires on the front. I say there's going to be stress on the driveline unless there is a center differential between the front and rear. Unlike farm tractors, many TLB's operate a large time on pavement. Something will give in the front/rear imbalance. Either tire wear or internal iron.
That's a good idea. A mathematically inclined person would already know the answer. Which I am not. I'm just basing my assumption on my experiences with offroad vehicles and air down of tires.
I agree.
In my mind if an owner was replacing all four existing tyres with 4 replacements that were identical (but not necessarily the same size as the old ones) he should be good to go however much the new tyres differ in size from the old ones. That is of course without considering issues such as ground clearance, etc. I couldn't see anywhere where the OP said whether he was replacing all four tyres or just the front ones. If all four, see above. If just the front two, read on ..... There is an SAE standard out there - J2204, that gives details of the maximum recommended difference in tyre sizes on a 4x4 machine such as this one that does not have a centre differential and where the front and rear tyre sizes are the same. It's written around front-end loaders but will also work fine for the backhoe in question here. Paraphrasing the standard: - 1. The critical measurement is the circumference. Put a chalk mark on each tyre at the 6 o'clock position and a mark on the ground next to it. Drive the machine forward 1 tyre revolution and make a 2nd mark on the ground. Measure the distance between the marks and that is the tyre circumference. Repeat for the other three tyres. 2. Maximum recommended difference between two tyres on the same axle - 3%. 3. Maximum recommended difference between the largest tyre on the machine and the smallest tyre on the other axle - 4%. IMHO the size difference between the existing tyres and their solid replacements will actually reduce the stresses on the drivelines because of the smaller diameter.
Isn't that assuming replacing all 4 equal size tires? This backhoe has 24" or so rear tires, and no mention of changing the size there (less likely to get punctured typically). I thought front wheel assist had an overdrive built in to the front axle to help with steering, as mentioned. That makes a bind on hard surfaces going straight. Take out the overdrive with smaller tires and there's less bind, until you get to enough underdrive on the straight that is binds more, or you don't like the steering performance.
Assuming you have a Centre diff lock changing only the size of the fronts, not all 4 by the same amount is going to play havoc with the manufacturers calculations and cause excessive stress. There have been reports in the press of cars with permanent four wheel drive having drive line failures caused by only renewing fronts when they wear out rather than all four and that difference is marginal compared to six inch diameter difference. The idea looks great though. Graham
I revisted the OP .......... "I ordered a set of Mclaren solid tires for my 310SL." To me the words "a set" indicate all 4 tyres. I hope the OP will chime in and tell us if that is not the case. "A pair" would give a completely different impression.
if your replacing all 4 tires then no issue on diameter or binding when in 4 x 4, the smaller tire will give less stress on the driveline, you will just lose a small amount of ground clearance, the 6 inches has to be divided by 2, 3 inches top and bottom and if the solid tires dont squat as much as the air tires then you will lose less, you need to measure from the center of the hub to the ground with the air tires on the machine then put all 4 solid tires on and measure from the same mark on the hub to the ground to see what the difference is..
I am sorry I am only changing the front tires. Rears will remain pneumatic. Also incase it was missed I am returning these and getting a larger size that is a lot closer in size to the original tires.
I think I would agree with you and try to get a tire closer in height to the original. Let us know how they work when you get them.
I agree.
When you get the new tires it would be interesting IMO to do the measurements of circumference and see whether or not they fall within the J2204 maximum recommended 3%/4% differences in my post above.
How would I do this with the large rear tires being different that the front?
I got the lager set yesterday. It might be a while before I get them mounted. I'm going to wait till I get called out to work on the rail road. Its the reason I bought them.
Sorry I didn’t explain myself too well. Use the chalk mark method above to measure the circumference of the existing pneumatic tyres before you remove them. Then repeat the process once you have the McClaren tires installed. It would be interesting to compare the measurements between the two types of tyre. Maybe a photo to show how they compare in diameter like you did before.
A point to add along with Nige's last comment. The front wheels should be free wheeling ie not in 4 wheel drive for an accurate measurement. If they were engaged, they could be skidded along by the rear wheels.
^^ And as a extra test you could measure them both ways... engaged and not, just to see what happens.
I wonder how much of a price is difference from a normal air tire. I spent $2500 to replace my all 4 old tires. 440\80 R28
Got the bigger size. Standing side by side the hight looks the same. I feel much better running the taller tire. These tires are heavy! 360lbs each. Took almost all I had to flip them up.
Those look a lot better on there.
This is what the rail road does to front tires This tires has 1100hrs on it And probably only about 25% of that time working on the rail road
Yikes! I hope that the hard tires will last you longer.