Upsizing Tyres - User Experiences

[drof]

Hi All,

I'm keen to collect some feedback and information from those PS owners that have upsized tyres over the OEM tyre diameter, as this is something I'm looking at pre-delivery on our new PS.

I'd like to understand what has been fitted and worked, any clearance issues (with either guards or towbars) and also general feedback on gearing/auto trans response, acceleration, economy etc...

As way of background, below are some of the common options that people seem to have fitted comparing diameter/%/sidewall (please add others):

18"
265/60R18 (OEM) - dia=775mm, 0%, sidewall=159mm (many options available)
265/65/R18 - dia=802mm, +3.5%, sidewall=172mm (BFG K02, Geolander G015 etc options)
285/60R18 - dia=799mm, +3.1%, sidewall=171mm (200 Series OEM - many options)

17"
265/65R17 (OEM equivalent) - dia=776mm, 0%, sidewall=172mm (many options available)
265/70R17 - dia=803mm, +3.6%, sidewall=186mm

One of the main reasons I'm considering upsizing is because on the 18" rims the sidewall height of the 60 profile OEM tyre is only 159mm. Once deflated for beach work, there won't be a lot of height left in the sidewall and may not be able to go quite as low with pressures compared to higher side walls, which will reduce footprint length (I regularly run my 265/65R17s at 15psi on the Challenger without issue).

Thoughts/feedback/discussion encouraged.

Drof

[old Jack]

Hi Dorf,

If I was buying a new PS then I would push to get Triton 17' rims and tyres fitted.
Cheaper tyres , more choice and higher sidewalls.

No secret my choice of tyres are Cooper ST Maxx, they suit my application very well and I am happy with their performance and life on and off road having 70,000km from the first set and 40,000km on the second set and thy are about half worn..

Sizes choices are ;

LT245/70R-17 780mm dia. ( this would be my choice)
LT265/65R-17 775 dia.
LT265/70R-17 816mm dia. (unlikely snow chains would fit and clear)
LT275/70R-17 817mm dia. (very unlikely snow chains would fit and clear)

LT265/60R-18 781mm dia.
LT265/65R-18 808mm dia.
LT265/70R-18 816mm dia. (unlikely snow chains would fit and clear)
LT275/70R-18 817mm dia. (very unlikely snow chains would fit and clear)

OJ.

[drof]

Thanks Old Jack,

Aware of you preference for ST Maxx and 17" option - I think 17" makes sense too, I just hadn't thought about a factory exchange option and wasn't that keen on aftermarket rims. I'm going into the dealer tomorrow and will test the waters on swapping of rims on delivery.

What are you thoughts on going up to a tyre of around 800mm diameter (+3%) on the PS and the trans. On the test drives I noticed that it's already quite willing to want to take higher gears for lower revs/economy, and with taller tyres (albeit small), I'm wondering if the problem will be more noticeable?

Personally, I wish they had kept the PS with 17" rims like the Challenger was (and Fortuner is!). I don't normally like changing too many of the factory fitments on our vehicles as when it comes time to re-sell things seem to be better when you can offer a pretty stock looking vehicle.

Drof

[Gregzzzz]

Hi Drof,
from memory, I think there may also be some legal requirements regarding the speed/load ratings of the tyres that on the vehicle as supplied 'new' by the dealer. So for instance the dealer has to supply a 110H tyre new, but after that you can change to a lower speed rating, S, say but will still need the 110 or higher load rating.

[old Jack]

Hi Drof,
from memory, I think there may also be some legal requirements regarding the speed/load ratings of the tyres that on the vehicle as supplied 'new' by the dealer. So for instance the dealer has to supply a 110H tyre new, but after that you can change to a lower speed rating, S, say but will still need the 110 or higher load rating.

To comply with the ADR's and if the vehicle is classed as an MC, which the Pajero Sport is then the requirement is to have a minimum load index of what is specified on the vehicles tyre placard but the speed rating can go down to N (14Okph). That said most good quality AT tyres in LT construction have a minimum speed index of Q (160kph).

OJ

[old Jack]

Thanks Old Jack,

Aware of you preference for ST Maxx and 17" option - I think 17" makes sense too, I just hadn't thought about a factory exchange option and wasn't that keen on aftermarket rims. I'm going into the dealer tomorrow and will test the waters on swapping of rims on delivery.

What are you thoughts on going up to a tyre of around 800mm diameter (+3%) on the PS and the trans. On the test drives I noticed that it's already quite willing to want to take higher gears for lower revs/economy, and with taller tyres (albeit small), I'm wondering if the problem will be more noticeable?

Personally, I wish they had kept the PS with 17" rims like the Challenger was (and Fortuner is!). I don't normally like changing too many of the factory fitments on our vehicles as when it comes time to re-sell things seem to be better when you can offer a pretty stock looking vehicle.

Drof

Hi Dorf,

I think the 8 speed auto in the PS, would have no issues with a taller tyre around the 800mm mark, the unknown is how the Adaptive Learning Function will cope with this change. I use the gear paddles in "D" all the time on my PB and it changes the shift points when I use "D" and let the computer do the gear changes.

If you are towing heavy then sticking to standard diameter tyres is still most likely the best option.

Unfortunately you will not know until you have tried this yourself.

OJ.

[waz123]

I have been running 285/60-18's for 6 months now. They fit perfectly on the PS, there is about 3mm clearance at full lock and fill out the wheel well nicely. No scrubbing on my PS and the spare fits in it place with clearance of the OEM towbar - not sure about the Hayman Reese bar though. They haven't missed a beat offroad and having an aggressive AT tread aren't too noisy either. Haven't tried snow chains as yet - not sure how well that will go under full lock. The reason I went this size after much research, more choice, better pricing and fit looks great with no lift and stock everything else.

[old Jack]

Hi Waz,

Have you tested full lock and full compression on the front suspension?
I would be most surprised if 285/60R-18 do not rub being 12mm taller and 20mm wider.
What brand and model tyres do you have?

OJ.

[waz123]

Full lock is not a problem no scrub at all on my PS - haven't checked the full compression, but haven't had any issues offroad on an otherwise stock setup. I'm running Toyo AT2 which is a far better compound than what comes with the PS from the dealer. The installer was a bit wary of it fitting, but checked everything at full lock and clearances and was suprised how well it fit. There is 30-40mm clearance to the wheel well (front and back) and more to the top of the wheel well (I'd have to measure that, can't remember).

[old Jack]

Thanks Waz,

The Toyo AT2 in a 285/60R-18 is a unquie tyre, as it is a passenger construction tyre but extra load rated to 120 which is almost the same load rating as many 10ply Light Truck construction tyres. This got me intrigued, I actual thought it was a printing error as I have never heard of a "P" tyre with such a high load rating so I looked up the US Toyo website for more info. According to the US website yes it is 120 load rating but it also says this tyre is approved for a 8" to 10" rim fitment, I believe the genuine Pajero Sport rims are 7.5" x 18" so this is a potential problem in regards to Toyo warranty and comprehensive insurance cover (if it can be proved the tyre and rim size caused or contributed to the accident). If you have fitted after market 8" wide rims then there is no problem.

I suspect they fit as they are only 24mm larger in diameter than factory tyres and being a Passenger Construction tyre the tread width will be about 15-20mm less than a a LT285, my guess is the tread width will be about 220mm to 230mm.

OJ.

[drof]

I have been running 285/60-18's for 6 months now. They fit perfectly on the PS, there is about 3mm clearance at full lock and fill out the wheel well nicely. No scrubbing on my PS and the spare fits in it place with clearance of the OEM towbar - not sure about the Hayman Reese bar though. They haven't missed a beat offroad and having an aggressive AT tread aren't too noisy either. Haven't tried snow chains as yet - not sure how well that will go under full lock. The reason I went this size after much research, more choice, better pricing and fit looks great with no lift and stock everything else.

Thanks Waz, this is exactly the type of feedback I was chasing. I've going to go the 265/65R18 route - about the same diameter as your tyres but 20mm narrower, so am assuming clearances won't be an issue. Fingers crossed on the towbar but the limited feedback I've picked up on that so far sounds like it will be OK.

Drof