Big rims and lower profile offroad tyres, pros and cons..

[mud4b]

Hi all.
Just thought i would put this up here as "blinging" your 4wds is becoming normal. Is anyone running big rims and low profile offroad tyres, how do they go offroad since there is stuff all flex in the sidewalls? any problems any benefits?

The largest i ran was 17" rims with 35" tyres but im talking smaller tyres in the sidewalls again..

cheers mark

[jasonw]

i have a ns pajero with the std 265/60/18 tyres and im finding im getting a rough ride off road ive done the same track in a defender and it seem to ride better pajeros have a good reputation for ride quality so im wondering if its down to the tyre profile being to small to give the cusion effect dunno

[grazza]

Pro: erm...
Cons: being on a 4wd, for, you know, 4wding, even more wankerish than usual

[mud4b]

i have a ns pajero with the std 265/60/18 tyres and im finding im getting a rough ride off road ive done the same track in a defender and it seem to ride better pajeros have a good reputation for ride quality so im wondering if its down to the tyre profile being to small to give the cusion effect dunno

Good point i guess, i figured it would be the case also..

cheers mark.

[mud4b]

Pro: erm...
Cons: being on a 4wd, for, you know, 4wding, even more wankerish than usual

I knew there would be a few comments like this.. sorry bud but i don't follow the herd..

cheers mark

[bogged]

Since when is
""blinging" your 4wds is becoming normal"

[Gwagensteve]

I guess it depends on the driving you're doing -

I think petersen's apply a 50/50 rule -

so biggest rim for a 30=15
32=16
35=17
40=20

I reckon there's something in that.

more rim than that figure will lead to a poor ride/rim damage. Less rim than that might equal poorer lateral stability.

I think i'd prefer more than a 15" rim at over a 35" tyre. Remember that BFG launched the 37" krawler in a 17" rim a long time ago - I reckon they did their homework and worked out what gave the best performance.

I'm running a 34 with a 16 rim and I'm happy with the lateral performance.

I know this doesn't directly address the 24" rim bling question, but I guess the point there is that if it has less than 7.5" of sidewall, it's going to bring the suckage offroad.

Steve.

[mud4b]

Since when is
""blinging" your 4wds is becoming normal"

Since when hasnt it?

examples.
good one for you, nissan guys getting the chrome grills, because its bling..
chrome mirrors, chrome parts, clear lights, name brand just for the sake of having arb on it, mickey thompson rims, craploads of lights, ect... Think about it really and not many people that buy the brand name stuff are buying it for the use/ or quality of it, blinging has been around for a while now..

cheers mark

[mud4b]

I guess it depends on the driving you're doing -

I think petersen's apply a 50/50 rule -

so biggest rim for a 30=15
32=16
35=17
40=20

I reckon there's something in that.

more rim than that figure will lead to a poor ride/rim damage. Less rim than that might equal poorer lateral stability.

I think i'd prefer more than a 15" rim at over a 35" tyre. Remember that BFG launched the 37" krawler in a 17" rim a long time ago - I reckon they did their homework and worked out what gave the best performance.

I'm running a 34 with a 16 rim and I'm happy with the lateral performance.

I know this doesn't directly address the 24" rim bling question, but I guess the point there is that if it has less than 7.5" of sidewall, it's going to bring the suckage offroad.

Steve.

Some very good info here steve, im not talking 22" rims here either but since this is a general question i guess they must be included.

cheers mark

[coxy321]

I know it was just sales/advertising, but a while back on one of the 4WDA DVD's MT did a speil on why you should run bigger rims (used their red GU as an example) on bigger tyres.

The main Pro that they were pushing was that you get less sidewall roll on the bigger rims (smaller sidewall) - no other reason really.

[-Nemesis-]

I think within reason, bigger rims are better. You get better lateral stability which is a major bonus. You only 'need' enough profile to bag enough for traction over obstacles, so long as you get a decent footprint, I reckon bigger is better.

Remember unless you're running massive bias comp tyres with treaded sidewalls, you're only after a longer tyre footprint when you reduce pressures, that's where your traction comes from. Having 5 inches of blank sidewall bulging out is of no benefit, they do love snagging tree roots and rock edges though.

Then you get much better handling on the way home too. Enough profile to allow a good footprint when pressures are down is it I reckon. I'm not saying go low profile like car tyres, but I reckon 35's on 18's would be way better than 15's etc.

[bushwalker]

i run 35s on a 16 inch rims way better than 15's more steering control just my 5c worth

[98lux]

Roly is running 20" rims with 40" tyres on his GQ comp truck.

[spamwell]

Pro: erm...
Cons: being on a 4wd, for, you know, 4wding, even more wankerish than usual

wow the insight and thought put into this fantastic information has made everything so clear to me, now i have all the help i need to do exactly what i need to do to enjoy my four wheel drive for my specific use.


anyways

definitely more steering control, obviously a little less rim protection and what not.

[chimpboy]

Probably less weight.

Less sidewall flexing, less traction, less "footprint" as te tyre won't spread as much when it is aired down.

More costly, fewer tyre options.

I think 16" rims are probably the sweet spot for cost, choice, weight, performance these days. But just as 16s are more common than they used to be when it was mainly 15s, we will probably start to see more and more 17s...

[Gwagensteve]

Nemesis - I understand the longer rather than wider footprint issue, however, with a larger rim, there is less sidewall to deform when you air down so the tyre can't grow in length as much.

IE if you have 10" sidewalls you can let 5" of height out of them which will give you a much longer footpring gain for the same diameter as a 5" sidewall aired down to 2.5" tall.

(An extreme example, but you get my point.)

I say there's a balance, and I'd have to say the 1/2 and 1/2 rule as a maximum rim diameter works for me.

PS Chimpy - for the same diameter overall, a bigger rim will make for a heavier tyre/wheel combi than a smaller rim.

Steve.

[chimpboy]

PS Chimpy - for the same diameter overall, a bigger rim will make for a heavier tyre/wheel combi than a smaller rim.

Really? I was wondering so I said "probably".

[Gwagensteve]

Apparently. I guess it stands to reason - Aluminium and steel are heavier than rubber - there's less material in a sidewall than a wheel.

It'll be part of the reason most forms of motorsport have standardised at around a 17" rim - It seems to be diminsihing returns after that.

The drive to 20" and over rims is mostly cosmetic AFAIK, even in road cars - it doesn't miraculously equal better handling or traction- In most cases, where, say, 18" wheels are standard and, say, 19's are option, consensus seems to be that the optional larger rim normally hurts handling and ride. The BMW M3 is a case in point.

I don't see any reason that 4WD's are any different.

Steve.

[blurredvision]

Trophy Trucks in the States are running 17's just to clear the brakes that they need to run. I would think that running larger you would be selling yourself short on the suspension that the Tyre sidewall offers to supplement the rest of your suspension.

[Gwagensteve]

TT's don't generate any lateral G's to speak of though compared to other forms of motorsport - they tend to run very low roll stiffness and slide corners rather than drive them.

Steve.

[booflux]

My wifes Prado and my mates Lux both run 32s on 17" rims, it works fine on the beach and for light to medium offroad. Like you I used to run 35s on 17s an my Lux and loved the combo never had a drama of not enough sidewall bagging etc.

I say go for it imo 15" black sunnies scream wanker but then everyones opinion is different

[-Nemesis-]

I know the overall tyres were rather large, but didn't the US entrants that won our main buggy comp the other year run 20's?

The footprint idea would be an interesting thing to compare, to see how much it really effects it, or whether a bigger rim will simply be closer to the ground at the same psi. Kinda hard to get the head around, but I would have thought the main bearing on footprint length would be the tyre diameter, not the rim. Wouldn't the rim have to touch the ground to stop the footprint growing? Then you get sidewall stiffness factor, obviously that would hinder huge rims (as in 22's and 33"s etc...)

Hmmm.... How can we test this. Would love to see side on shots of a 35 on 15" and a 35 on 18" rim at 10psi for example.


I guess it all comes back to horses for courses and the type of driving people want to do.

[chimpboy]

15" black sunnies scream wanker

That is a very good point. It's not like bad taste bling is a new thing

[turbo gu]

I'm looking at 35s on a 17/18 rim for my GU wagon. Already runs 35s on 16s but need to update tyres and seen most driving is on tar or touring may aswell reduce the sidewall for a bit better handling plus the wife wants some bling

I run 37inch Krawlers on 17 inch rims on my ute and never had a problem with no enough bag in the sidewall plus handles quite well on the road

[GRPABT1]

I think it would depend alot apon tyre design and construction too, a radial 35X12.5X15" a/t is going to handle alot differently to a simex ET 35X12.5X15". Getting the right combo is what is important. Take formula one for example, the very top level of tyre design, so much so that the tyre itself acts as most of the suspension in the vehicle and opposite to norm in a fast car they run a high profile as the tyre design affords them that ability.

As with most things in 4bying it's a balancing act of trying to figure out what works best for you offroad with as little sacrifice to onroad as possible for the desired gains.

[Gwagensteve]

I run 37inch Krawlers on 17 inch rims on my ute and never had a problem with no enough bag in the sidewall plus handles quite well on the road

Which is exactly my point - BFG basically pioneered the 17" rim and it was based on performance offroad not fashion.

A 37 on a 17" rim has the same height sidewall as a 35 on a 15" rim.

Steve.

[pigletracing]

GU's now come standard with 17" rims for a few reasons,1 being brake clearence, I know 15" rims do fit but theres not much spare space, on my comp rig,(GU front end & 15" alloys) the 2 front rims now have deep gouges all the way round the inside, where rocks & debris is picked up then get caught between the caliper & rim then groove there way out. in 1 year I ran 37" on a 15" rim & a teem mate ran 37" on 18" rims, & with not enough side wall flex or sidewall to protect the rim he went through tyres & rims IE rim biting the side wall out or rim smahing / dent out of shape by rocks at speed. I just did the usuall puntchers
IF comping go the biger side wall option, but with plenty of caliper space, 16" or 17" would be good,,, keep your 24" rims for road unless your running 40+ tyres
my 2 cents PIGLET

[mike_nofx]

Hi all.
Just thought i would put this up here as "blinging" your 4wds is becoming normal. Is anyone running big rims and low profile offroad tyres, how do they go offroad since there is stuff all flex in the sidewalls? any problems any benefits?

The largest i ran was 17" rims with 35" tyres but im talking smaller tyres in the sidewalls again..

cheers mark

What particular (or at least a little more specifically) tyre/rim combos are you thinking of?

[RN]

Hi all.
Just thought i would put this up here as "blinging" your 4wds is becoming normal. Is anyone running big rims and low profile offroad tyres, how do they go offroad since there is stuff all flex in the sidewalls? any problems any benefits?

The largest i ran was 17" rims with 35" tyres but im talking smaller tyres in the sidewalls again..

cheers mark

For what it is worth.

In days of old we ran 15" steel rims with the 70 or 75 'performance' profile tyres. They would roll a bit on the sidewall under heavy cornering but were better than the run of the mill tyres on the other work vehicles.

Now we have 45 profile tyres on 18" and they tend not to squirm about under heavy cornering. The pros...hard to tell when they are flat as they are so stiff in the side wall. When only checking by giving it a 'visual' you can be mistaken that the tyres are inflated correctly. The older tyres use to make the car sit awkward when they were flat and it was easier to spot.

The lower profile tyres send a lot of shock through to the chassis.

Overall for 4WD purposes , my preference would be to keep to the norm for a combination of comfort and performance.

[GRIMACE]

15" black sunnies scream wanker

That is a very good point. It's not like bad taste bling is a new thing

what about 16" black sunnies??? I never knew that buying a cheap rim in black was bling or gonna make me more wankerish...

Then again i don't mind being a wanker, maybe I should have kept the 17" black steelies...

I always new i was a wanker just never knew that black steel wheels that were cheap and easy to replace was increasing my bling and wanker stakes!

Learn something new everyday...