OK to go up a tire size on GX Auto new model

[Dtuner65]

Hi
I would like to know if it is O.K to go up 1 tire size to 265/70/17 on a GX. I am looking at buying one and have read some issues with auto transmission not locking up. I would be towing a camper trailer (750KG no elect brakes) on occasion. Also how much does it affect the speedo? Are there any other potential issues?
Dan

[Spook1205]

Hi Dtuner,
this is a subject you will get a few different opinions on I guess. People choose to go a bigger tyre for reasons that suit there driving needs. Larger tyres do look better visually, hopefully the guys that have them on chip in on this for you. I really only 4wd on sand so I have very limited experience on 4wd track/trails ect to others on here.
I personally keep to the specified size simply because it was engineered for that size and 6th gear is a pretty big overdrive and I spend much of my driving at highway speeds.
It will have a small influence on the Speedo and bring the visual speedo reading closer to vehicles actual true speed. In saying this the vehicles speed is measured by the wheel speed sensors and is very accurate to real speed, the speedo you see has a tolerance built in so you think you are going faster than you really are. All manufacturers that I am aware of do this, Subaru has the biggest tolerance that I have noticed being faster by about 8km when doing 100km/h. I find the Fortuner about 4km faster on speedo compared to internal vehicles speed on a scantool and GPS at 100km/h.
cheers, Luke

[White One]

That torque converter lockup is a long ongoing issue since Fortuners came out , and is still the same on the new models. I thought they had fixed it but no they didnt. Ive seen mine engage 6th on a flat open road at 60kmh with light throttle , then still not engage again till 120kmh not towing. So all im saying is dont make a tyre choice based on that issue alone. For towing in hilly areas the factory tyre size works well im my opinion.

[Dtuner65]

Thanks for the reply. I mainly wanted larger tires for a little more clearance,larger side wall and bigger footprint for off road. I have done this on another vehicle but it was a manual and worked out well. I just did not want to create issues with the torque converter lock up by increasing tire size. Has anyone done this mod?
Dan

[uansari1]

I’m really looking forward to this thread...been asking about going up a size in terms of how much trimming is really required to the front mudflaps, but thought that the forum had become much less popular in the past year.

[White One]

Forums in general have been less popular since Facebook groups have been gaining momentum. the Fortuner groups are quite busy though i generally store information in here when it needs to be more permanent.

[uansari1]

Forums in general have been less popular since Facebook groups have been gaining momentum. the Fortuner groups are quite busy though i generally store information in here when it needs to be more permanent.

Thanks for the heads up...I didn’t realize people were still on Facebook. 🤣

[Skippa]

For what its worth i have the GX model 2017 and have put 265/70/17 BF Goodrich All terrains on with no issues, slight rub on the front mudflap at full lock reversing out of the driveway until they wear a little and the speedo is accurate to within 1km so all good..

[Benicio]

For what its worth i have the GX model 2017 and have put 265/70/17 BF Goodrich All terrains on with no issues, slight rub on the front mudflap at full lock reversing out of the driveway until they wear a little and the speedo is accurate to within 1km so all good..

Hi Skippa,

Do you notice any difference in acceleration from a standing start?
Also what about going up hills & on the highway?

I'm thinking about going up to that size myself & am weighing up the pros & cons.

[Skippa]

Hey Benicio,
i got them fitted from the start, but no issues with acceleration, I've towed a 2T tool trailer over to Whyalla and back to Melbourne still overtaking etc..

[uansari1]

Does anyone have recommendations on tire pressures to run on KO2s? I just upgraded from the factory Dunlops (stock pressure of 29psi/2bar) to KO2s in LT265/65/18. The tire pressure calculator at tiresize.com indicates that I should be running at 35psi/2.4bar, but want to know if you gents have any guidance on whether this sounds correct.

[Spook1205]

The higher the pressure the better wear on tyres as less likely to scrub outside edges if your alignment is good.
Downside to higher pressure is reduced comfort in ride.
Run 35 see how it feels against 30