The Big wheel Gearbox debate
- Thread starter GordyT6
- Start date
South...ish Nottingham.
They are load rated to 690kg so good enough for a t28.
They are load rated to 690kg so good enough for a t28.
What class is a T6 caravelle?
I though t28 was 2800kg total.
Either way it never bothered me too much.
Load rated tyres are more important.
Either way it never bothered me too much.
Load rated tyres are more important.
I've purchasd a new kombi from swiss vans hammered them down on the price got to haggle did me a cracking trade deal on a set of 20" wolfrace assassins with tyres but they cannot fit them they getting thrown in the back of the kombi as its something to do with warranty only covering optional extra upto 18"wheels
Ok, folks, thicky newbie here: learning a lot, but getting more baffled. Now understand that the smaller number on the tyre's sidewall (40/45 or whatever) is the ratio of sidewall to width ( I think) but 16 to 20 something is the wheel diameter is it, or not? My Fiesta has 205/40/17s, but the wheel measures 18.5 edge to edge
When gearing is discussed, do you learned folk mean that as long as I keep the wheel plus sidewall radius the same, gearing is unaffected, ie I could drop to eg 15s and have larger sidewall off road style tyre's?
When gearing is discussed, do you learned folk mean that as long as I keep the wheel plus sidewall radius the same, gearing is unaffected, ie I could drop to eg 15s and have larger sidewall off road style tyre's?
Yes, you could fit larger profile (percentage of the width) tyres if fitting smaller diameter wheels.
Use an online calculator to determine how a new set up compares with your existing tyre sizes.
Example calculator here>>> Will They Fit - Online Wheel and Tyre Fitment Calculator
Input your existing tyre size in box on left and new size on box on right and hit 'calculate'. This will then give both values for circumferance, speedo error etc and give you an idea whether you are increasing or decreasing overall diameter.
I can't remember the exact persentage but you would be boarder line with your reading under but it can read over a lot more . The kit cars I build have to be tested on a rolling road so always set them reading fast. The persentage will go up as you go faster so at 100 mph it could be 6 or 7 out but by then you are getting point any way.
If you get to a hundred, you'll have far bigger problems than points - more like a ban for gross excessive speed eh @Thogg!
T
Thogg
Guest
Yep... tonight's night shift consists of doing the paperwork for someone who saw fit to do 112 mph when the outside temp on Dartmoor was -4 and everything was frozen solid and white! His wheels were standard though!
Oh my...
I shuffle around like some OAP when it's sub zero.
Book him Dano.
Dickhead deserves everything coming to him.
Morning all, interesting topic this and seems to crop up all over the internet as mentioned. My way of looking at this is from a simple physics point of view. The force on the gearbox is due to the engine/gearbox combo trying to spin the front wheels around the van or spin the van around the wheels and the opposing forces this creates (think Newton once stated this!?!). Clearly it is difficult to do the latter due to 2-3 tonnes plus gravity being a bit harder to shift than 50kg ish of alloy and rubber to rotate, so the wheels turn and the van moves forward. The forces opposing are driven by the laws of physics and as you may recall from school Force = Mass x Acceleration. So the forces are the weight(mass) and rotational acceleration of the driven wheels versus the weight and horizontal acceleration of the van forwards. These should be equal (more or less if we ignore other minor frictional losses).
As you can see increasing the weight of the wheels, the weight of the van or sticking your foot to the floor will increase the forces (and therefore gearbox strain). As far as I can see, and please tell me if my thought process is flawed here, but increasing the weight of the wheels by a few kgs is a pi$$ in the ocean compared to having a fully loaded van or flooring it everywhere. Clearly the worst combination is to have heavier wheels, a massive load and giving it beans all day long, and the latter two can have a much more dramatic impact on the forces.
Ultimately the engine is only able to put out so much power and torque and this will limit the mass x acceleration, more mass less acceleration, and vice versa, so as far as I can see it the way to get the maximum force (or potential gearbox/driveshaft damage as alluded to in this thread) is to have a heavy right foot, and wheel weight becomes pretty insignificant compared to this.
I would say that if you want to run bigger wheels, do so, and if you are really worried, the just drive a little lighter on the gas, or take some load out of the van as they are much greater factors. Common sense would also point to this, what's less effort for you, to carry one bag of sand wearing heavy shoes or two bags wearing trainers?
As you can see increasing the weight of the wheels, the weight of the van or sticking your foot to the floor will increase the forces (and therefore gearbox strain). As far as I can see, and please tell me if my thought process is flawed here, but increasing the weight of the wheels by a few kgs is a pi$$ in the ocean compared to having a fully loaded van or flooring it everywhere. Clearly the worst combination is to have heavier wheels, a massive load and giving it beans all day long, and the latter two can have a much more dramatic impact on the forces.
Ultimately the engine is only able to put out so much power and torque and this will limit the mass x acceleration, more mass less acceleration, and vice versa, so as far as I can see it the way to get the maximum force (or potential gearbox/driveshaft damage as alluded to in this thread) is to have a heavy right foot, and wheel weight becomes pretty insignificant compared to this.
I would say that if you want to run bigger wheels, do so, and if you are really worried, the just drive a little lighter on the gas, or take some load out of the van as they are much greater factors. Common sense would also point to this, what's less effort for you, to carry one bag of sand wearing heavy shoes or two bags wearing trainers?
