tyre size benifits??

[islandvitara]

ae fellas,

seen guys wanting to run 35s and other dudes runnin 33s or 31s on the zooks ect..

whats the difference between them all besides the size? does a 35" tyre have a big advantage over a 33 or 31" tyre?

say one is running 33s - what would be a reason for he/she to go up to a 35?

traction? the look? does a 35" tyre do better off road then 30s/31s/33s ect???

anyone have a personal preference??

just interested in why some fellas run 35s over the smaller sized tyres

cheers islandvit

[Gwagensteve]

I'll answer this in more detail when I'm at home (i.e not at work) but in short a larger tyre provides both more traction (not always, depending on surface) a better shaped footprint (not always, depending on tyre) and the ability to roll over bigger obstacles due to the larger radius.

However, the biggest reason to run a taller tyre is that it's the only realistic way to improve ground clearance at the lowest point under the vehicle - the diff centre.

Shaved diffs, portals, SPOA etc can all improve ground clearance under all or some o the axle, but a larger tyre also has the benefit of the other stuff I mentioned above.

Steve.

[islandvitara]

hmm...so is there a any real benifit/advantage of a 35"tyre over a 33"" tyre??

im lookin at possibly getting 33s down the track but 35's have crossed my mind but i dont think id need to go that big. i currently run 31s on my sierra now but am looking at a larger diamter tyre down the track, i think 33s will be the pick over the 35's

if so has anyone run both these size tyres?? 33s and 35's and what wld you prefer overall?

[alien]

on zuk diffs, for reliability, 31's is the best bang for buck size... 33's you'd get away with but with more breakages of axles/cvs etc... 35's i'd say you'd be dreaming to have a reliable rig.... let alone trying to engineer it (make it legal).

[want33s]

How about some pics of the 'new' body fitted up.
I reckon 33's are big enough especially if you still want to drive it on the street without attracting too much attention.

[islandvitara]

really!!! so you would run a 31 at most on a std zook dif would you say you'd have to or preferably go a lux diff on 33s?? bcos a 33 is as big as id go - later on as in enda the year

[islandvitara]

will do when i get home

[nicbeer]

as gwagon will say it all depends on the weight of the right foot and terrain traction u are on. sand/mud is low traction so >31 will be ok. but rocks no on zook diffs that is

[Dee]

I'm on standard zuk diffs & wheelbase with 33's.
In the process of installing aftermarket chromo axles though.
another pro of a big rolling radius is better approach/departure angles.

I would go to lux diffs if I wanted to run 35's, not purely because of the tyre size, but more because with a 35" tyre I'd want a longer wheelbase, which on a SWB chassis would mean custom suspension (coils?) so one may as well upgrade diffs while they're there. Also the increase in width would be beneficial.

I honestly believe a stock wheelbase is too short for 35" tyres. Especially with lift to fit them. I'd want absolute minimal suspension lift & just do some big guard cutting. Even better again would be a longer wheelbase with comp cuts to fit them. not exactly road drivable though...

[islandvitara]

I'm on standard zuk diffs & wheelbase with 33's.

you had any dramas with your setup?

[islandvitara]

as gwagon will say it all depends on the weight of the right foot and terrain traction u are on. sand/mud is low traction so >31 will be ok. but rocks no on zook diffs that is

so what your saying is to go lux diffs with bigger rubber?

[Gwagensteve]

hmm...so is there a any real benifit/advantage of a 35"tyre over a 33"" tyre??

im lookin at possibly getting 33s down the track but 35's have crossed my mind but i dont think id need to go that big. i currently run 31s on my sierra now but am looking at a larger diamter tyre down the track, i think 33s will be the pick over the 35's

if so has anyone run both these size tyres?? 33s and 35's and what wld you prefer overall?

A) Under the NCOP you won't get anything over a 28" tyre legal on a sierra diff, on a passenger ADR'ed sierra. A 31 is *just* possible on a commercial sierra (i.e one that came on 16X4.5" rims and 6.00X16tyres)

B)Yes, a 35 is better than a 33, for the same width.

D) a 12.5" tyre is too wide for a sierra for

E) I've run/had a hand in building 28's, 30's, 32's, 34's, and 35.5" and 36" tyres on sierras, all on sierra diffs. yes, the taller tyre works better. Wider tyres work worse for the same height. I.e a 35 13.5 won't work as well as a 35 10.5 on a range on conditions.

On high traction surfaces (shopping malls, rock, hard dirt) the wider tyre is superior.

There's no point to running a 33 on a hilux axle over 31 on a sierra axle - all the advantage of the 33 is absorbed by the size and weight of the hilux axle.

you'll be fine on 31's - you'll pretty much go anywhere you want on them and your car won't be cop bait.

Steve.

[islandvitara]

cheers thanks steve thats pretty much all i needed!! but yad run 33s on std wt diffs - right?

[Gwagensteve]

Yes, but not at 12.5 wide, (the height/width ratio of 33's is totally wrong and they suck on any slippery surface - very poor directional control)

Also, not without doubletough front axles and solid pinion spacers front and rear.

Steve.

[DeWsE]

For obvious reasons above a larger tire size is generally the goal, to help climb over larger obstacles which say a smaller tire will get hooked up on (refer a skate board wheel verus a car tire). But something to keep in mind though is wheelbase when talking about the advantages over a smaller tire. So in comparison, if we were to talk about a stock wheelbase Suzuki (SWB), then I believe (Others opinion may differ) that when you put a larger tire on, you improve roll resistance over obstacles, but you decrease the stability on both axis. So the car is more likely to roll forward, backward and side to side. Most people know this, so in a bid to build a better off roader they will generally increase the width of the car and the length (wheelbase).

So to focus on your question which I’m going to relate to a SWB zuk, seeing as this is a zuk site, not general tech. If you are asking if a 35 is better then a 31/33 on a zuk (assuming it’s stock wheelbase, or even for arguments sake modified within the parameters of the wheel arches) then 33’s are the maximum size you would want to go before you really start to affect the balance of the car, and the effective use of the suspension cycle.

Now there is always exceptions to everything, and it will always come down to personal opinion what is right and what is wrong. In a perfect world everyone would be driving super expensive buggies which do everything including making Café latte express. But in the real world people will build what they can afford, then wheel the piss out of it, enjoy it and get used to its limits. So when it comes to personal preference, it’s always going to be gauged on someone’s tolerance for what they have.

Something I wrote age’s ago… I don’t know how correct it is, but in theory it sort of works.

“Well I have been thinking about a formula, and it would be said that 100 with 37s is a good balanced wheel base. So I took the standard zuk with 26 inch tyres @ approx 80 inch wheel base. Now I looked at the difference between a 37 and 26, which is 11 inchs and difference between a 80 and 100, 20 inchs

So simply 20 / 11 = 1.8 inch increase with every 1 inch increase in tire size.

I think people like to say 100 to 104 inch wheel base is suitable, so I think you could round that to 2 inch with every inch of tire.

This should help the car stay stable and have a decent ramp over.

So using this theory a 35 tire should have a wheel base of 9 x 2 = 18 over stock = 98 inch overall

So how many flaws (Not floors, thanks grinbo) do you think this formula has?

Obviously it would only work with a zook.

Note this is only based on a max tire size of 37. “

Read more - http://www.outerlimits4x4.com/ftopic462 ... light=base


When this happened I was packing, especially because I was about two foot off the ground and I had to roll backwards. The bouncing was because of bad suspension design (Chassis extension was like my penis.. too long). This just points out the problem of sort wheelbase and larger tires (33’s in this case) and stability.



With more wheelbase this would have been easier, but as it is he’s probably relying on the guys out the back a fair bit!



Exceptions like this, just make you wish you had the balls to total a car and just live with what you got. Tim Hardy on 35’s


Damn this thread took off when i was writting this... hope it's relevant still

[islandvitara]

cool so just outa curiosity what do you have on ur zook?

[DeWsE]

cool so just outa curiosity what do you have on ur zook?

My 59 Holden FC rolls on some shiaty tires which need to be replaced... My zuk is rotting in paddock lying on the chassis.......

I'd liek a new one, one day

[islandvitara]

cool wat about you steve what do you roll on?

[Gwagensteve]

I'll answer in more detail tonight. DeWsE has raised some relevant points. I'm currently on 9X34 16 Swampers.

Steve.

[dank]

I'm on 34x10.5s with double tough cromo cvs and shafts up front. 2inch body 2 inch susp and it feels great on angles. wouldn't go any higher though. looking to shorten my 2 inch extended shackles at some stage. I snapped 3 cvs in 3 months on 31s silverstone extreme because I was driving with not enough thought and too much right foot. You can drive on standard running gear and 31s and not break anything just need to be aware of the limitations. same goes for 33" and 34".

some guys on here are building standard height zooks on 37s...lots of cutting apparently can be done!

[MUD-PIGSIERRA]

All this talk and no one mentioned having the power or gearing to actually turn bigger tires........

Im going from a 31" MTR to a 33" 10.5 tire later in the year basically because I want a better diff clearance and I have the gearing to do it. Basically the ruts and general tire size on tracks now are really 33" at the smallest and bigger these days so im getting hung up on the diffs and getting stuck so thats my reason to go bigger. As Steve said for a Zook at least if i was to go a larger tire I would keep it at 10.5 wide at the most, once you start hitting mud and water and what not you gotta push more surface area and it really sucks the power.

[DeWsE]

Off topic.. Mud-pig.. i haven't seen you driving around yet..

[MUD-PIGSIERRA]

Im sure you will eventually ........

[alien]

interesting theory on the wheelbase...

my front diff is 6" forward and rear 1" back, giving me a total of around 87" WB (not measured to confirm)... running 31's this is a VERY stable setup, stable enough to pass the lane change test 'as is' with no cheating or modification other than inflating the tyres to 35psi to reduce sidewall flex.

The other advantage of more WB up front is the engine weight is now slightly behind the front diff - the zuk is far more balanced on road now.

By DeWsE's calculations though, going from a 26 to a 31 is a 5" increase, so my WB would then be roughly 9" extended... somehow i dont think the rampover is quite as attractive then... and itd look REALLY odd with 90" WB and 31's =)

[joeblow]

for years i have run 33's, diff gears and lockers, the zook is 1500kg's and plenty of torque throught the driveline. in 14 years i've broken 3 front axles, now that number would increase if i was running a different setup. with 35's you will go backwards as far as wheel travel, reliabilaty and handling in concerened, and if you own a real zook, you don't have hilux diffs[ oh...and i have never broken a diff centre!...]. 31's are good...33's are even betterer.

[nicbeer]

Mine is 31 on 7s and feels stable cept on the steep up and downs as in pic.

thats with 2" + 2". locked up front and welded ass.

not broken anything in axles/diffs. only a couple unis so far and thats in mud/sand/slimey rock and hardish rock area .

[Gwagensteve]

The tyre size vs wheelbase argument is an interesting one. As tyre size increases, so does height and hopefully traction. These two things add together to create a double whammy. A stock sierra doesn't seem too short for it's tyre size because it can't generate enough traction for it to become an issue.

So for me, the problem isn't that a sierras wheelbase is too short to run, lets say, a 35, it's that the traction generated and the height (generally) required to run those tyres starts to cause the problems.

I always claimed with each size increase that it wouldn't work because the car would drive onto the tailgate, but basically, I've been proved wrong, but we're trying to build cars as low as possible to try and keep the car stable. Were also using autos, SPUA, and generally know when to get off the power. We are running RUF, which adds 40mm of wheelbase and does radically change the balance point, but that's way below what the formula woudl tell you the cars needs to be functional with a 35.

However, once you're hooking up a 35 with gears you WILL have the ability to unweight the front end - the thing is, it's not worse than a car with 31's in the same position, only that with more traction you can get into a steeper angle and then it will start to happen.

Also, the added traction of the bigger tyre will cause more "hop" as the suspension unloads. Think about it like this - we might be running the same spring rate (leaf) as a stock sierra but we've got maybe three or four times the traction woth lockers and 35's- and that's why the springs will be unable to control the axlewrap and the car starts to hop - (leading to breakage) the spring rate required to support the car is way less than the rate required to control the axle. This is one of the disadvantages of leaves.

The common build path to 35's seems to involve a SPOA on a SWB sierra. The tyres alone result in about 4.5" of lift, and a SPOA normally accounts for 5". Is a 35 too big for a stock sierra wheelbase? Nope, but a SWB with 9" of lift will suck on big climbs. It's not the tyres fault. To get height out, often, the spring rate is dropped to flatten the spring. This only makes it worse.

It is true though that more wheelbase will allow for more traction on big climbs. I'm currently running a LWB with 55mm over stock WB and plan to add another 250mm to the wheelbase to allow me to really hook up tyres in the 35-36" range - but to be fair, we're now talking way beyond the parameters of normal operation and I'm really chasing the most capability on big ledges and to be able to keep the power in on really technical sections. The rest of the time, I'm just going to have a really un-maneuverable sierra that bellies out everywhere. That's OK, I know what I'm setting out to do - a SWB will drive all over it on tight, flatter terrain, and I'll own the steep climbs.


Hope this adds something to the discussion.