Nissan Patrol 4x4 (Africa)

I got my old tyres (BF Goodrich 265/75r16) with the vehicle about 2 years ago and put about 35000 km on them. I decided to change because they were 6 yrs old and got hard. They were also not good on wet surfaces and developed uneven patches which several people blamed for the wobble between 90-100 km/h (after sorting out most other possible sources).
Yesterday, (28 Oct 2022) i got new tyres from Rob's Tyres (pretty good deal, I think) on recommendation and facilitation from Antony and Tinus, respectively (Thanks btw ). They are Maxxis Razr AT811 265/70r16. Funnily, they were exactly the same height as the old worn down BFs. 265/75r16s would have been 25% more expensive, which was too painful for me at the moment. On the first trip back to Joburg they seemed smoother and quieter than the BFs , but sadly the wobble was not gone . I will see how they do in rain.
The speedometer and the RPM readings (100km/h @2150 RPMs) were exactly the same as with the old tyres. Well, not surprising because thet are the same height. However, the GPS reading (i use WAZE) was 90 km/h (with Maxxis) instead of 95 km/h (with BFs) when the speedometer showed 100km/h. And now the funny bit , the tyre size recommended by Nissan (label in the door) is 235/80r16, which is the (almost exactly) the same size as the 265/70r16. So, i would expect that the speedometer is calibrated to this size. Hence, be closer to the (true) GPS reading. In fact, i expected that with a larger tyre (compared to the recommended/calibrated one) the speedometer would "underread" (100 km/h when really going 105 km/h). Am i totally off here or are the errors of margin so large that this makes sense in some way?

Most speedometers in my experience over-read by at least 10km/h.

On the one hand I guess manufacturers have to try and ensure that speedos never under-read as that would leave them open to blame if somebody got caught speeding but I have often wondered whether they add a bit more than necessary for safety's sake.

Also keep in mind that the size of a tire is entirely a nominal value, and over and above that the actual rolling diameter will be affected by rim width, inflation pressure and wear.

Thanks for the feedback, Peter. That's good to know.

The Patrol speedo as most other speedos can be adjusted to correct the speed indicated. The adjuster is a small pod with a plastic screw type adjustment in the centre of the top surface of the pod. The same goes for the rev counter.

I took my GQ the Reef Industries just south of Carlton Centre in Johannesburg. The rev counter was all wrong after I fitted the V8 engine. They could not get it 100% correct but at least between 2000 and 4000 it was fairly close to correct. But that was what the pulse of a v8 does when the revcounter is expecting a pulse from a 6 cylinder.

The guy got my speedo to be spot on with the 33s fitted. He showed me how to adjust it if it was not 100 correct after fitment. Unfortunately I don't think I will be able to identify the correct adjustment pod today.

Thanks Malcom.

Klaus you need to go say hello to ant . Wil sort you out quick quick....he is a monster when it comes to finding the wobble in a patrol

A quick update on the new Maxxis: I got them sorted out by Rob last week. They refitted all the tyres on the rims and got them properly balanced. Since then the wobble is gone.
Rob told me that one of the rims may have caused the wobble or added to it. However, he couldn’t tell me what exactly is wrong with that rim. I’m using it as a spare now.
Nevertheless, I would like to rotate all five tyres, so that they wear evenly. Hence, if anybody has a 16 inch steel rim that you are happy to part with for a reasonable amount, please let me know. I attached a pic of the spare wheel.

I have one for you yes please come and visit .

Great. Thanks Tinus.
It would be nice to get to know you in person finally. I will contact you via WhatsApp to arrange a date/time.
Best, Klaus