Ranger/BT 50 Tyre Size

Under ADR Australian Design Regulations the only legal change to tyre size is what is specified on the tyre placard inside the drivers door or manual supplied with the vehicle.
Perhaps you need to sit down and work out what "only 15mm bigger in diameter than what I have" makes to the vehicle. IMHO only a fool changes tyres size. The manufacturer matches everything to the vehicle from engine, gearbox and diff and tyre size for optimum operation of the vehicle. Changing tyre sizes will only move the vehicle from optimum specification.

Walter

This is probably what you're seeking:
NCoP discussion: Electronic Stability Control and Vehicle Modifications

Hi Walter
the 265/75/16 tyres you are looking at are only 3mm bigger than the option tyres that are available for the Wildtrack 265/60/18 . So it should be no worries but check.
Matt

Hi Walter,
I run BFG KM2 265/75/16 tyres on my 2012 BT 50. According to VSI 08 here in Victoria, we can run up to 50mm change in diameter over standard so for me this tyre complies and so I get 20mm extra clearance under the body approx. Unfortunately all states have different regulations at present.

Although some might suggest otherwise, IMHO I am not crazy to do this as the BT does not have that much clearance from stock and given that many tracks in the Victorian High Country need clearance for safety then I am happy with this increase. With the saggy suspension on the BT the body will sag down to standard height anyway once any weight is applied. At least I keep the axle clearance.

Speedo reads correctly with this tyre and it does not foul the body or suspension. I don't notice any difference in performance and possibly only a slight increase in fuel consumption.

I have run my own swerve test (not too violent) and have not been able to induce a fault MIL with the ESC so I believe that the stability system is functioning correctly with this tyre upgrade. If the increase was way too far outside the ECU parameters then a I would expect a fault to be induced. If ESC can't work properly with such a change given the different tyres and wheels available as standard from Ford and Mazda and the fact that loads are always changing and the fact that I could have a trailer attached then it is not much use is it. I am confident the increase has not compromised this system.

Regarding ESC, it would also have to cope with that fact that people might fit a roof rack with loads and the extra weight of a front bar and rear bar. These would alter the vehicle dynamics and Mazda sell these as options. Yes, I think ESC can cope with a slight increase in tyre diameter.

Here in qld it is also legal to run 265/75/16. My new ranger will be moving that way when the originals wear out.
ESC is a reactive system, not pro-active. It CANNOT assume tyre size, road traction levels or any other guesses about loading etc.
It merely reacts to losses of traction at the wheel and brakes various wheels until traction is regained. You think the same sized cheap chinese mud tyre as the oe highway terrains is going to have the same grip on a wet highway?

My 2013 BT50 came standard with 265/65/17 and i was thinking about a wider tyre with a higher profile until I checked the width I had left to play with...virtually nothing. The standard alloys are a +55 offset which means the tyre fits v.close into the suspension. The optional rims shown in the Mazda brochure are CSA Jackals which are available in +20 to +35 offset which would allow the wider tyres seen in many pics around the place.

Soo...My dilemma is simply just a reminder to also check the available width to be able to run a larger tyre and not just the height.

Cheers
Brenton

Hi Everybody,

Thanks for all the responses, it has certainly given me some direction. It appears that 265/75/R16 tyres are legal but may not be accepted for Mazda warranty purposes. I telephoned Mazda Customer Service at Headquarters and asked them about fitting larger tyres and about modifying the suspension. They told me that they advised against ANY modifications. They said that although the mods may work they could void the warranty if they caused a problem with the vehicle. They did give me an address to write to regarding technical mods and I posted a letter yesterday. In the mean time I will run 265/75/R16 on a separate set of rims for bush work and use my normal tyres on another set of rims for touring and caravan travelling. I will have the rear suspension stiffened up but have not yet decided whether to go for a 50mm lift.

Cheers,

Walter