Kingsize24
Well-known member
THIS! Or do the paint dot method and measure the distance center to center after one full revolution. Both flat and at max PSI will be the same.
Ram 3500 - Spare tire options for 37s.
- Thread starter Longship
- Start date
THIS! Or do the paint dot method and measure the distance center to center after one full revolution. Both flat and at max PSI will be the same.
Kingsize24
Well-known member
BTW... I've tried to do the 37 in the back before. It's 100% the hitch and its location as mentioned above. It pushes the wheel and tire combination so far forward that the axle will not cycle, and the diff cover hits the tire on compression. The width between the frame is JUST under 37", so 95% will fit without issue if it wasn't for the hitch.
mog
Kodiak Buckaroo
Agree, the hitch setup on the Ram is HUGE. Nothing against Ram for making such a stout hitch, but it sure takes up a lot of space. When I mounted my rear winch bumper, I had to go with a smaller physical sized winch just to clear the hitch. So perhaps if you don't need the max tow rating (just using the hitch for bikes, hauling an ATV trailer, etc), perhaps going to a smaller aftermarket hitch might be a option to fit a larger spare in the stock location?
Kingsize24
Well-known member
p nut
butter
Still doesn’t make sense to me (I’m hard headed 😂).
ie Some TPMS detects an under inflated tire by using the speed sensor. Meaning, if it’s rotating at a faster speed than specified tire size, warning pops up. This is because the effective diameter (or radius) or rolling circumference is smaller than a fully inflated tire.
rruff
Explorer
There is very little stretch in the tread (steel belts)... not zero but tiny. So long as the tire bead isn't slipping and the tire isn't skidding on the ground, then the tire circumference dictates how far you travel per wheel revolution. The radius at the contact patch is the wrong part to be focusing on.
Probably better to envision the tire tread like a track on a tank.
renottse
Member
That was my starting point, used the drop hitch. Cut the center section out of the standard hitch so the frame still had the end sections bolted in.
The drop hitch will still interfere though, so I had to make up new side sections that extended rearward. Used the center section off a Curt, used the mounting holes on the Curt side plates for the template and extended the side plate length, mounted it all up to work out where the landing of the center section should be and welded that in.
I added a winch so it landed lower than standard, I can live with the compromise.
ITTOG
Well-known member
There is tire deformation when underinflated which can reduce the circumference a little but it is minimal unless severely deflated. Or completely deflated, then you are riding on the rim which all will agree is a different circumference than the tire.
IdaSHO
IDACAMPER
A bit more specifically, when weight is on the tire the distance from ground to wheel center will vary with PSI, so even though the circumference of the tread doesnt change, the wheel/tire speed will. A tire at full pressure will result in lower wheel speed than at lower pressure. This is how speed and or abs sensors can be used for things like TPMS.
rruff
Explorer
They would need to key off very small circumference changes due to pressure. The radius to the contact patch is irrelevant.
Kingsize24
Well-known member
This
IdaSHO
IDACAMPER
I never said anything about radius.
With the same road speed, a tire with lower pressure will turn faster than one with high pressure, as the DISTANCE from road to wheel center is different.
Simple geometry.
Kingsize24
Well-known member
That's actually incorrect. The speed, regardless of PSI will always be the same. Because the tire from point to point, if you use the same reference, will always cross the same amount of distance.
IdaSHO
IDACAMPER
Perhaps I should clarify, as there are obviously few ways to look at this.
I purposely omitted the word radius for a reason.
With a lower PSI tire the distance (okay... .radius) from ground to center is different.
But thats the point. No way, no how is that irrelevant.
That difference is the perceived change in circumference the wheel sees.
And inflation for ABS/wheel sensor based TPMS systems are FAR more sensitive than some in this thread would think.
They do not need a severely deflated tire to trip the system. They can be, and are accurate to a few psi
I purposely omitted the word radius for a reason.
With a lower PSI tire the distance (okay... .radius) from ground to center is different.
But thats the point. No way, no how is that irrelevant.
That difference is the perceived change in circumference the wheel sees.
And inflation for ABS/wheel sensor based TPMS systems are FAR more sensitive than some in this thread would think.
They do not need a severely deflated tire to trip the system. They can be, and are accurate to a few psi