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Reducing tyre grip - smallest tyre to fit on 15" rims

5K views 49 replies 21 participants last post by  russellw 
#1 ·
Hi...

Just recently bought some second hand 205/65R15's to put on my diff locked EF. At first they were great, car was smooth like a BMW dipped in WD40. Then they started getting their grip back, so I decided I'd go burn some of it off, which turned out to be a mistake - now they grip worse than I've ever seen! The car understeers everywhere and thumps really loud when turning at low speeds.

Anyone know any good tips? Coating the tyres with something? What's the maximum safe tyre pressure that you can run? And what's the smallest, most sh!thouse possible tyre that will fit on a 15" rim?
 
#2 ·
your post sounds a bit contradictory, but maybe it's the way i'm reading it.

you should be able to get 195/65 R15s on your rims, but i dont know about anything skinnier.
 
#6 ·
Grip isn't dependent on width of the tire - its down to compound and weight. Weight you ain't gonna change, so get a different compound...

If you want a gripless tire - head to kmart and buy the cheapest shite they'll fit - its sure to be the hardest compound known to man - no grip in wet or dry... Even better if its some bodge korean brand you've never heard of....

But - it does seem weird to diff-lock you car, and then want crap grip - unless you are dragging on the w/e and swap tires then...
 
#7 ·
Car has a "CIG locker" because the old LSD stopped locking and I couldn't afford a new one and single spinning was not an option... Tyre grip needs to be minimal because the car is my daily driver.

I'm not sure what width the rims are, I thought they were 6.5" but judging by the replies they're prolly a 7". I think they're the 15" EF XR6 mags. Current tyres are old Dunlop Monza 200's. If anyone is looking for a grippy tyre, this is it. Clean em up with a bit of circle work and they'll stick to the road like bubble gum! Even better than my old worn 225/55R16 Bridgestone/Dunlop combo.

XR8 Lamah, how gripless is the KMart Korean stuff? I might have to bite the bullet and fork out the $$$ for a brand new set of them as the car is really getting on my nerves.

Is there something I can do to my current tyres? Greasing them up overnight? Is there a solvent that hardens rubber? What's the max pressure I can run in them? (Currently at 52psi and the grip is still there) It's just that I paid $50 for this set and I don't want to lose them so soon...
 
#9 ·
Re: Reducing tyre grip - smallest tyre to fit on 15

qwikcorty said:
why not pick up some 14" steelies from the wreckers of another falcon, the tyres on them are bound to be 185, like dads gl wagon. easy for skids!
Have thought about that... Problem is I want to keep my good tyres on the front for braking & cornering and I'm a bit worried about the visual aspect of it. Cops don't take kindly to people who run steelies just on the back... The load ratings on the 185's on 14's should be ok though, right?
 
#10 ·
try a bit of brake fluid on the rear tyres? Makes them smoke pretty quickly. Just makes sure you have a fire extuingisher handy as I have seen this been done before.

Used to do it to my bro's petrol RC car just to see it catch a light some times.
 
#12 ·
Having smaller rims on the rear to the front I'm fairly sure is illegal ( fairly sure having thinner on the rear to the front is as well ).

I can't really vouch for the k-mart tyres, since I've never actually bought them myself, but a car I had, had a set from the previous owner - and they were absolutely crap.

I'd be seriously worried running 52psi in those tyres - I would have thought they'd be very close to blowing out at that point ( especially if you do anything "interesting" with them ).

I'm not really sure what you should do - but be careful on changing rims, in case you end up defected or invalidating insurance . . .
 
#13 ·
Cool! Great ideas guys!

Tyres are soaking in the brake fluid as we speak. I'll take it for a test drive in a few hours and let 10psi out of them on the way. I'll let you know how it turns out.

TICKFD6 - I need no rear traction because I have no diff, not the other way around.
Single spinning = no sideways = bad.
Double spinning with no grip = slow, but sideways (on private property :wnc:) = acceptable.
 
#15 ·
Re: Reducing tyre grip - smallest tyre to fit on 15

Cancerman said:
Cool! Great ideas guys!

Tyres are soaking in the brake fluid as we speak. I'll take it for a test drive in a few hours and let 10psi out of them on the way. I'll let you know how it turns out.
.
Please just turf them away!

Otherwise you will be comming back in a body bag and the countless others you will take out!

The idea of doing that is just down right silly!
 
#16 ·
the "CIG locker" is the problem here,a normal lsd does slip abit,especially going round corners,a locker diff dont!!! thats why it would be clunking round corners...also you would need heaps of power to keep em spinning with a locker,they give full 100% drive...watch for broken axles....
 
#17 ·
Re: Re: Reducing tyre grip - smallest tyre to fit on 15

laminge said:
Please just turf them away!

Otherwise you will be comming back in a body bag and the countless others you will take out!

The idea of doing that is just down right silly!
Tyres actually have a hell thick bit of wire, thread and other stuff on them which the brake fluid won't eat through. You can actually drive pretty far on just this stuff, so I reckon she'll be right.

philstoj said:
the "CIG locker" is the problem here,a normal lsd does slip abit,especially going round corners,a locker diff dont!!! thats why it would be clunking round corners...
Yes, I noticed...
 
#19 ·
This is a real worry. Lockers, whether CIG or spools are not sensible on the road, you seem to have found that out.
Go and fit a tightly packed LSD center. This will give you most of the benefits the locker has, but without any of the problems. You will be able to use the biggest stickiest tyres your guards will accommodate, and you won't compromise it's handling.

A couple of other points which others have brought up, wider tyres DO give more grip, brake fluid on the rubber is a real BAD idea, and 52psi in most tyres IS fine.
 
#23 ·
Re: Re: Reducing tyre grip - smallest tyre to fit on 15

SiX_iN_a_RoW said:
please for the sake of less than $200 go tp a wrecker and get an LSD, dont put yourself and others in danger!! thats the most ridiculous thing I have ever heard!
I have yet to see an LSD for $200 over here, and even if I did, I couldn't afford it. I fail to see how my CIG spool puts others at risk. The understeer is very gradual and predictable even in the wet, chirping in carparks is only mildly annoying, my front tyres are perfectly roadworthy and Soxx reckons that 52psi IS fine, so I might go put 12psi back in...

Look, I understand all ur comments about the torque differentiating capacity of my locker, and its various disadvantages. But my last LSD put me in teh financial shite when it decided to quit after 9 months. I AM saving for a "Lockright" diff, which apparently is like a Detroit locker for BTR diffs and doesn't wear out.
Lockright - $650
LSD - $550
New friction cones for the old LSD - $220
CIG spool - $30
Beggars can't be choosers. The CIG spool STAYS damnit!

Btw, after a night of soaking, the brake fluid was only mildly effective and only for the first few minutes of the drive. I don't plan on repeating the experiment.
 
#24 · (Edited)
Re: Re: Reducing tyre grip - smallest tyre to fit on 15

Soxx said:
A couple of other points which others have brought up, wider tyres DO give more grip
;)
*Only* if the compound is better....

http://www.chris-longhurst.com/carbibles/index.html?menu.html&tyre_bible.html

http://www.autospeed.co.nz/cms/article.html?&A=0996 ( can only get the first page - but it has the relevant info on it anyways . . )

Oh - with the brake fluid ( eeeek ! ) - if it wasn't completely dry when you put em on the car, you'd be likely stripping paint off where any spray lands.. ( brake fluid + paint = badness afaik ).

be real careful with what you try - you don't a messy result :)
 
#26 ·
Re: Re: Reducing tyre grip - smallest tyre to fit on 15

xa-coupe said:
is this thread for real ??????
Cancerman, firstly I'm glad you're in WA. Now before you stop reading, be very careful what you do here. If you put tyres smaller than 205/65 on an EF or do all sorts of other silly things then your car is unroadworthy & insurance co's won't touch you with the proverbial barge pole if you have a prang. Can you afford this?

I'm not the fun police, but surely dirt roads aren't that far away, and it does rain from time to time as well. Ease up & you'll save a heap of dough on fuel, tyres, speeding/dangerous driving fines & you'll be able to afford the LSD again.
 
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