4.8GRX Tyre size

Getalbo
Newbie
Newbie
Posts: 9
Joined: 30 Jan 2011 20:06
Full Name: Lester George Talbot
Nickname: Getalbo
Home Town: Joburg
Current 4x4: Pajero SWB 3.2 D i D
Nissan Patrol 2006 4.8GRX
Home Language: English

4.8GRX Tyre size

Post by Getalbo »

What is everyones experience on this issue. 16" or 17 ". Obviously it effects drive train ratios etc., and to some extent consumption.
Your thoughts and advice please?
IanT
Patrolman 1000+
Patrolman 1000+
Posts: 1234
Joined: 17 May 2013 10:43
Full Name: Ian Temperley
Nickname: IanT (aka) "The Joker"
Home Town: JHB
Current 4x4: 1995 GQ 4.2 Petrol (Turbo Charged) (Hell Boy)
2008 4.8 GRX Umkombe
Home Language: English
Been thanked: 92 times

Re: 4.8GRX Tyre size

Post by IanT »

The 4.8 GRX standard tyre size is 17 inch it is fairly easy to find good AT tyres and even muds in 17 inch these days I was running 265's but a lot of the guys run 285's or even 305's
Zantus
Senior Member
Senior Member
Posts: 137
Joined: 30 Apr 2009 14:50
Full Name: Barto de Koning
Nickname: Zantus
Home Town: Port Elizabeth
Current 4x4: '01 4.5 GU & '91 4.2D GQ
Home Language: Afrikaans
Has thanked: 3 times
Been thanked: 5 times

Re: 4.8GRX Tyre size

Post by Zantus »

16"vs 17" doesn't have an effect on ratio's, it's the outside diameter that matters in that regards, i.e. you can have a 15" rim with an outside diameter of 35", which will be way worse than a 17" rim with 31" diameter.

Comparing two tyres with the same outside diameter, but different size rims, the bigger rim gives you more lateral stability, but the smaller rim allows you to deflate more without the chance of de-beading, so that will be better for off-road use. There are more benefits/negatives to both, just giving you a rough idea and I want bring the point across that rim diameter differences should not be confused with tyre outside diameter differences.
User avatar
Peter Connan
Moderator
Posts: 6011
Joined: 10 Sep 2010 07:21
Full Name: Peter Connan
Nickname: Piet
Home Town: Kempton Park
Current 4x4: 1996 Patrol 4.5SGL
Home Language: Afrikaans
Location: Kempton Park
Has thanked: 1067 times
Been thanked: 985 times

Re: 4.8GRX Tyre size

Post by Peter Connan »

The 16" or 17" you refer to is the rim size, and assuming you buy a tire that fits on the rim you have, it has no direct bearing on the overall size of the wheel, nor on the gear ratio, fuel consumption nor any other aspect of fuel consumption.

More on this later.

Unfortunately, with metric tire sizes it is quite a calculation to determine the tire's outside diameter (which is the factor that affects the overall gearing). It goes like this (and sorry in advance as I will be working in inches):
The tire size is for example 285/75R16, and this is what it means: The tire width (at the widest point, not the tread) is the first number set (in this example 285mm). The second set of numbers is the aspect ratio. This is the sidewall height, but expressed as a percentage of the tire's width. In this example, the sidewall height is thus 285/75 = 213.75mm Convert this to inches (by dividing by 25.4) and you get 8.4". The third number set is the diameter of rim that the tire fits on. To get the outside diameter of the tire, multiply the sidewall height by 2 and add the rim diameter: 8.4*2+16 = 32.8" Bear in mind that these figures are nominal not exact, they change by at least an inch during the life of a muddy and they change when loaded and depending on tire pressure, and it becomes evident that you needn't worry too much about the commas.

Now, the 4.8's standard wheel size is around 32". I feel a 33" is about ideal, while some are prepared to go all the way to 35". Also bear in mind that width will also play a role, particularly in fuel consumption.

My reasoning for always going up one size is as follows: most times when you get stuck, it's because you have run out of ground clearance. Most times, this is due to a middle-man that has been created by a variety of vehicles. If you have just a little bit more ground clearance than "mr. Average", you avoid most of these issues.

Now rim size: for an off-road vehicle, the higher the sidewall the better. It allows the tire to form a longer footprint when deflated for better flotation, and keeps the rim further away from the edges of the potholes, thus significantly reducing the risk of tire damage.
However, on smooth roads high sidewalls are a disadvantage, as they are not as directionally stiff. Thus high-speed handling suffers a little bit, and may come off the rims more easily during violent high-speed manuevres.

So while I have not given you an answer, I have hopefully given you tools to get your own answer?
Mag ons ons kenniskry met lekkerkry aanhoukry.
User avatar
David
Patrolman
Patrolman
Posts: 723
Joined: 17 Dec 2009 12:42
Full Name: David Prinsloo
Nickname: David
Home Town: Stellenbosch
Current 4x4: 2006 Patrol 4.8 GRX
Home Language: Afrikaans
Location: Stellenbosch
Has thanked: 2 times
Been thanked: 48 times

Re: 4.8GRX Tyre size

Post by David »

On a 4.8 there is apparently a problem going to 16 inch rims as they interfere with your larger brake calipers so I would suggest sticking with your 17 inch rims but go to a 285 (33"). They fill the wheel arch better and give you a little bit more ground clearance.

The down side is it will look like you are heavier on petrol as your speedo will be close to 100% but your trip meter will under-read. In reality there is little difference in consumption.

The up-side will be that your car will look better and perform better off road :thumbup:
2006 Patrol 4.8 GRX Tiptronic Y61/GU(4)
ARB Bullbar, BZT rear bar, TJM 2" Suspension, Snorkel, LT 285/70/17 BFG KO2's, 40L Engel

Stop Rhino Poaching Supporter!
User avatar
JohnBoyZA
Site Admin
Posts: 1339
Joined: 02 Apr 2009 14:34
Full Name: John Murray
Nickname: John Boy
Home Town: Bloubergstrand
Current 4x4: Patrol GRX 4.8
Home Language: Afrikaans/English
Location: Big Bay, Cape Town
Has thanked: 1046 times
Been thanked: 230 times

Re: 4.8GRX Tyre size

Post by JohnBoyZA »

If you struggle to remember the formulas like me ... then you're welcome to use the attached.

My only comment is that sometimes you might need to catch up to mates and you might end up driving these speeds, then don't opt for the higher profiles.



Not recommended...!
Attachments
jb_tyres.xlsx
(13.22 KiB) Downloaded 391 times
Nissan Patrol, GRX, 4.8 (GU Y61)
User avatar
Marino4x4
Patrolman
Patrolman
Posts: 520
Joined: 19 Oct 2011 12:15
Full Name: Marinus Potgieter
Nickname: Marino4x4
Home Town: Bloemfontein
Current 4x4: Nissan Patrol
Home Language: Afrikaans
Location: Bloemfontein
Has thanked: 17 times
Been thanked: 84 times

Re: 4.8GRX Tyre size

Post by Marino4x4 »

Hi JohnBoy

Dit werk nou sommer lekker. Baie maklik om te gebruik.

Groete
Patrol 4.5 GL 1998

Terrain 4X4 Parts
Getalbo
Newbie
Newbie
Posts: 9
Joined: 30 Jan 2011 20:06
Full Name: Lester George Talbot
Nickname: Getalbo
Home Town: Joburg
Current 4x4: Pajero SWB 3.2 D i D
Nissan Patrol 2006 4.8GRX
Home Language: English

Re: 4.8GRX Tyre size

Post by Getalbo »

Thanks everyone for your input. I will stick with the 17 " which I have.
User avatar
Peter Connan
Moderator
Posts: 6011
Joined: 10 Sep 2010 07:21
Full Name: Peter Connan
Nickname: Piet
Home Town: Kempton Park
Current 4x4: 1996 Patrol 4.5SGL
Home Language: Afrikaans
Location: Kempton Park
Has thanked: 1067 times
Been thanked: 985 times

Re: 4.8GRX Tyre size

Post by Peter Connan »

David wrote:On a 4.8 there is apparently a problem going to 16 inch rims as they interfere with your larger brake calipers so I would suggest sticking with your 17 inch rims
16" rims fit on the 4.8, it's 15's that don't fit.
Mag ons ons kenniskry met lekkerkry aanhoukry.
User avatar
Alex Roux
Patrolman 1000+
Patrolman 1000+
Posts: 2627
Joined: 11 Jul 2011 10:54
Full Name: Alexander Roux
Nickname: Calculator
Home Town: Johannesburg
Current 4x4: 2004 GU 3TDi (Lexus) - aka "Witblits" (sold)
2005: GU TD42 - aka "Masewa"
1996: GQ TB48 conversion - aka "Skilpad"
1993: GQ SWB TB42 - aka "Shortie"
1985: MQ Patrol (Safari) SD33 - aka "Toro"
Home Language: Afrikaans
Has thanked: 49 times
Been thanked: 240 times

Re: 4.8GRX Tyre size

Post by Alex Roux »

Peter

Does this apply to all the 2005+ facelift models?
Or pre facelift too?
The 2005+ models came out with 17" standard, or only the GRX models, I think?

Christo's Chuck has 15" on (1999 model I think)
Mine is 2004 (pre-facelift) which still had the 16" as factory standard.
But I do not know if I can take 15"?
Skilpad, Shortie, Toro & Masewa
Post Reply

Return to “14. Rims & Tyres”

Who is online

Users browsing this forum: No registered users and 9 guests