zx Tyres?? 185/195?

[8304]

Hi everybody

i am running stadard tyres and 14" zx alloys on my my ZX at the moment. I would like to fit some say 16" wheels but am unsure how big - a - tyre you can fit into the back arch. I know that 195's will fit in the front arches but there doesnt seem to be much room between the wall of my current 175 tyres and the inner back wheel arch.

I know Pug 306's can fit large tyres on the back and they have the same floor pan etc right?

whats the widest 16" tyre you can get on the back of a zx without reaching for the angle grinder

[James.UK]

Not sure about the rear wheel arch clearance, but.. You wont get anything bigger than a 175 into the spare wheel cage under your car..

The cage was made to take a 165x65x14, so either you will have to make the cage bigger, or have your spare wheel taking up all the room in your boot..

[8304]

or i spose i might be able to source one of those space saving wheels??

i wonder if it would be possible to just do the thread in the boot for the spare wheel up until it pushes the wheel against the bottom of the boot, it would be a bit lower but i cant see it escaping....

the other thing is i could always just keep the spare as the same 175 and if i ever had a flat just stick it on temporarily to get me home or to the garage.....

[mezuk04]

Isnt the Zx good enough without over sized wheels

[8304]

the zx is indeed an outstanding car as it is but ive uped boost and fueling so it stands to reason that the grip should be uped too. I find it wheels spinning in 2nd in the dry and third in the wet so why not try and improve what is already a good car. Larger wheels with wider tyres can only improve the looks and the performance of the car still further.

each to their own though!

[robsons]

I've got a 5 door Volcane with 195's on 15" Pug GTi wheels and they're fine until I go over speed ramps and they catch. I'm getting a recon axle on the back and hopefully that will fix it. (I've a touch of the / \ on the trailing arms)

The aspect ratio change sure makes a better drive. (Same setup at 2.0 16V ZX)

[8304]

ahaaaa so 195 will fit. sounds like they are as big as i should go if they are rubbing slightly with a touch of / \ Cheers robsons and the others who posted.

alastair

[robsons]

OK it fits just (we're talking 2 mm here) so tyre choice will be critical. Note also that my worn trailing arm bushes will be helping it fit!

Inner clearance is OK and if it rubs more on the outer wings after the bushes are done then I'll jack out the arches a few more mm with some wood and a jack.

[8304]

i wonder if i went for 195 fronts and 185 backs as you only have to have same tyres on each axle for mot right?

i never have trouble with the back sliding its just the front understeering and sliding about.

is yours a turbo d?

[THELABMAN]

I'm not 100% certain on this bit I'm sure if you have different sized wheels back and front the largest wheels had to go on the back ie 15" on front and 16" on the back, you may well find the same applys to tyre width, ie 175 on front and 185 on back it would pay to enquire 1st.

[sooty]

When you say 'you're under steering' do you mean you have to turn more into the corner.???

If so, then your front end is too stiff, and you'll need to stiffen up the rear. The problem you are having with wheel spin, is where the body weight is being thrown back and lifting the front end.

So by stiffening the rear suspension with stiffer torsion and anti-roll bar, and not just by replacing the dampers which will do nothing to stiffen only resist the bumps better.

The best bet, would be to fit the rear suspension from a Volcane, to try first otherwise source retro fit bars if you can find any at a reasonable price. Because fitting wider tyres beyond standard is going to cause you problems with tyre drag(increasing your fuel bill), improve your chances of aquaplaning in the wet and see no improvement to speak of with the extra expence with these 195 tyres over the 185.

Next time you see FWD cars racing/rallycross/rallying on a track, watch how the suspension behaves when cornering.

good luck

[8304]

thanks for the response.

I experience understeere in the following situation:

comming off a roundabout - i find i have to be pointing where i want to go before i put my foot down because when its pulling away with the wheels turned ie around a corner or leaving a roundabout it just spins up and travels in a straight line rather than where i want to go (not enough grip)

the front has been lowered 40mm on harder springs but the back is as standard because one of the torsion bars was siezed causeing the puller bolt to snap off in the end so i will have to change the subframe completley if i want to play with the rear - ive heard its not too bad a job so i will do it somtime...-it will be worth sourcing one which has disks on the rear arms aswell i spose...

i will take note of race car suspension next time i see one...

[sooty]

This is my point about the front end being too stiff.
When you're cornering and pushing the boost, you are lifting the inner wheel because the weight is being thrown to the rear and the rear is not stiff enough to resist it and to keep the tyres in contact with road.

As I said watch the FWD when racing, they lift the rear inner wheel, not the front inner.

I have exactly the same problem with mine, and starting sort things out when the weather is warmer, but for now, all I can do is control the FORCE.

[8304]

yeah you are right i think because as that intial shift of weight to the back causes the front to lift some of the pressure on the front tyres is lost, this lets them start spinning and they keep spinning because dynamic friction is much less than static friction.....

sort the rear suspension is the conclusions from this then i spose..

what have you done to your zx to get 115bhp? is that proven 115bhp? - what do you rekon mine would be at 19-20 psi boost and fueling tweeked over time to suit?

cheers!

Alastair

[sooty]

The only way I can judge the 115 is by being faster than a Audio A4/Passat with 115 engine, Pug/Cit with a 110 HDI engine and as you say a Focus and many more off the mark.

The boost is at approx 18 psi, fuel adjusted to suit and cut back the fuel boost to reduce the smoke when on boost, and then Max rpm from 4500 to 5000 rpm.

Although it can rev to 5000 I never go that high, but when you're going up the gears you'll find its alot liverer going to Max of 4700. Because as you approach the limit at 4500 you start to slow to reach that standard limit.

But you MUST remember to turn the Max revs back for the MOT !!!!

As for con rods going through the side, the later engines of 97/98 before they went to HDI. Did have a problem as seen on various sites.

The only big thing to worry about with these engines is the Headgasket, if you continously boost to the max and cook it especally in the hot weather. Some people have fitted a front mounted intercooler to help solve this, but alot of expense and trouble to fit.