I have a gen 2 Pajero 3500 V6 and would like to know if I can run 255x75R 15's. I presently have 265x75R15's and 31x10.5's on the vehicle.
Wessie, I think it will be OK to change to 255/75R15 provided you change all the tyres. This tyre size will have a rolling radius that is nominally 7.5 mm (or 2%) smaller than the original size (265/75R15), so the effects on gearing won't be too dramatic. Your gearing will become shorter (by 2%) and this will mean that you will have slightly more tractive effort (2% more) available at any given speed in any gear, but that your top speed or maximum speed in any gear will be slightly less (also 2%).
I would be a little careful of fitting different size tyres to the front and rear axles. The Super Select transfer box incorporates a viscous coupling on the center diff. If you have different tyre sizes front and rear, the center diff will continuously have to compensate for this and the viscous coupling will continuously oppose the differential action (the purpose of the viscous coupling is to turn the center diff into a limited slip diff). This could lead to overheating and seizing of the viscous coupling (if you run in 4H a lot) at worst and at best will make it difficult to engage the center diff lock on the move. If your viscous coupling seizes, you loose the cool Super Select ability to run in 4H on tar and are effectively stuck with a part time transfer box...
By the way, the rolling radii on the 265/75R15 and 31x10.5 are not identical; the 31x10.5 is nominally 1% (or around 4.5 mm) bigger than the 265/75R15.
I would be a little careful of fitting different size tyres to the front and rear axles. The Super Select transfer box incorporates a viscous coupling on the center diff. If you have different tyre sizes front and rear, the center diff will continuously have to compensate for this and the viscous coupling will continuously oppose the differential action (the purpose of the viscous coupling is to turn the center diff into a limited slip diff). This could lead to overheating and seizing of the viscous coupling (if you run in 4H a lot) at worst and at best will make it difficult to engage the center diff lock on the move. If your viscous coupling seizes, you loose the cool Super Select ability to run in 4H on tar and are effectively stuck with a part time transfer box...
By the way, the rolling radii on the 265/75R15 and 31x10.5 are not identical; the 31x10.5 is nominally 1% (or around 4.5 mm) bigger than the 265/75R15.
Gerrit Loubser 
2003 Toyota Land Cruiser 100 VX TD
2003 Mitsubishi Pajero 3.2 DiD LWB A/T Gone & missed
1999 Nissan Patrol 4.5E GRX M/T: Gone & missed
1996 Toyota Land Cruiser 80 VX 4.5 EFI A/T: SOLD
2003 Toyota Land Cruiser 100 VX TD
2003 Mitsubishi Pajero 3.2 DiD LWB A/T Gone & missed
1999 Nissan Patrol 4.5E GRX M/T: Gone & missed
1996 Toyota Land Cruiser 80 VX 4.5 EFI A/T: SOLD
Gerrit,
It seams you da man to talk to with tecknical things,
I'll keep that in mind.
How will my Traction / gears etc be affected if I move up to a 33x12.5x15 or even a 33x12.5x16 (although, are 16s more expensive on 4x4s as well)
I have a polo at present with 16s, and theyre even more expensive than 17s etc. So maybe I'd stick to 33x12.5x15s.
Either way, I do definately want to go 33, and not 32.
What say you,
It seams you da man to talk to with tecknical things,
I'll keep that in mind.
How will my Traction / gears etc be affected if I move up to a 33x12.5x15 or even a 33x12.5x16 (although, are 16s more expensive on 4x4s as well)
I have a polo at present with 16s, and theyre even more expensive than 17s etc. So maybe I'd stick to 33x12.5x15s.
Either way, I do definately want to go 33, and not 32.
What say you,
Well, I say that if you can have 33x12.50R15 then you would definitely not want 33x12.50R16. Up here the Land Cruiser guys go to all sorts of trouble to fit 15" wheels in place of their 16" wheels. For an off road vehicle, you want all the rubber you can get and as small wheels as you can fit. More rubber means a softer ride and more grip, since you can deflate the tires more.
I find that the 33's on my car definitely improve ride quality on gravel roads, they probably improve traction although that's harder to measure and the gearing in my car can handle them fine, although your gearing may be different.
When going slower on harsh trails I deflate the 33's to about 18psi (that's pretty conservative) and the ride and grip improve a lot.
I find that the 33's on my car definitely improve ride quality on gravel roads, they probably improve traction although that's harder to measure and the gearing in my car can handle them fine, although your gearing may be different.
When going slower on harsh trails I deflate the 33's to about 18psi (that's pretty conservative) and the ride and grip improve a lot.