lift on KZTE

[007]

I want to fit 32" tyre on my KZTE. Does anyone know what lift will be required to fit 32" tyres on order for the tyres to clear the bodywork. Do I need to change any thing on the drive train?

[BenHur]

I am not sure about the lift but generally a IFS vehicle can not be lifted to much without other complications. Maybe a body lift would be better.

BUT

Are you going to do a ratio change as well? Remember that going from 245X75XR15 to 32x11.5xR15 means that you effectively enlarge the circumference of the tyre by 8.00" (203.14mm) which means the engine will turn slower at the same speed and have less power. The problem with a diesel is that you will now have to push harder on the accelerator at lower RPMs to maintain the same speed while driving. The bad thing with doing this on a diesel is that you are effectively now "over fuelling the engine which pushes up the Exhaust Gas Temperature (EGT). Too high EGTs is the main killer for diesel engines.

To calculate the change on your vehicle use a tyre size calculator that can be found here.

viewtopic.php?f=34&t=224

I used the calculator on the first link and it gave me this info on your proposed change

Your engine speed at 3000 will drop down to 2761 to maintain the same driving speed, which is quite substancial.

Replacing your 245/75 R 15 (29 x 9.65 x 15) tires with 292/74 R 15's (32 x 11.50 x 15's) would lower your finish line RPM by 239 RPMs

If your odometer has been calibrated for 245/75 R 15 (29 x 9.65 x 15) tires, replacing them with 292/74 R 15's (32 x 11.50 x 15's) would result in the odometer reading low by 7.95%.

[007]

My speedo is currently about 10Km/h out on 120Km/h. This is one of the reasons I want to fit bigger tyres. To gain some ground clearance is obviosly the main reason. I do have a SAC intercooler fitted. So I'll then have to re-tune the engine management system. I'm only looking at a 2" lift....max. I still drive around town, and I don't want it to be to top heavy.

[Family_Dog]

You might be better off considering 31" tyres, which will not have such a stressful influence on drive train and engine power, while at the same time providing some lift and truer road speed. All cars have an optimistic speedometer, to ensure you cannot hold the manufacturer liable for infringing speeding conditions.

I have 31" tyres on a 2.7i, but also have a OME suspension lift, and the combination is a good one on the the IFS, but I doubt I would want to go any bigger on tyre sizes.

-F_D

[BenHur]

I will try to explain more. I am not a diesel mechanic but this is the best way I can explain it. So if I make technical grammatical errors, please forgive me.

Unfortunately no amount of tuning will be able to compensate for the RPM change due to wrong ratios.

Your engine has an optimal efficient operating RPM (close to the torque peak in 5th) which is normally matched via gearing to about 110-120km/h which is the normal cruising speed on open road. If you now fit larger tyres the engine will be operating below that point so you will have to fuel it harder to have enough power.

It will almost be like driving uphill all the time. With a Turbo Diesel going up a steep hill it feels like the engine has enough power left to go up in 5th but because the RPM is coming down. The amount of diesel vs. air going into the engine is now more so you are over fuelling. That pushes up the EGTs. That is why they recommend you change your driving style with a diesel and actually gear down going up the hill to get the RPM back to the efficient operating RPM range.

With a petrol engine the accelerator pedal controls the throttle body which regulates the amount of air that goes into the engine via a butterfly and the vacuum created sucks in fuel. So at any given throttle position for example. half throttle the amount of fuel going into the engine will decrease as the engines RPM (vacuum) decreases.

But with Diesel engines the accelerator pedal controls the diesel pump directly and it pushes an amount of diesel into the engine directly related to the throttle body. Thus when, at a specific accelerator position, the engine RPMs go down the amount of diesel going in to the engine remains the same even though the volume of air going in reduces so then over fuelling happens and EGTs go up.

That is why diesel engines working hard at with the accelerator fully depressed tend to let a large amount of black smoke out the exhausts. This will happen more with your larger tyres which is thus bad for the engine.

[007]

THANX
Well, then in that case I think that 31"'s then the way te go. This should correct the speedometer error and won't have such a great influence on the ratio as the 32"rs or 33"rs.

From this, if you change the ratio, it'll overcome the problem of the low rpm vs feul issue. But that is something I'll maybe do later....

[BenHur]

Yes the 31s are a better match and most probaly you will not have to do to an exterme a lift (or maybe no lift at all) to get them to fit. Eric you should know

[pietpetoors]

007, the guy where I bought my 2700 i from also have a 2004 model 2700i. He fitted 32" tyres on 10" rims. He had to to a bit of cutting at the front fenders and had to do a 50mm body left.

31" fits perfectly. I fitted my 31" tyres without doing anything to the rest of the vehicle. The spedo is closer to the truth now, we tested it this weekend. When I do 120 on the clock it is 116 true speed.

You do not have to worry about the power and consumption, it is very much the same as with the normal tyres.

The 31" is worth every cent, it makes a huge difference when it comes to off-road.

The nice thing about our bakkies is that you can do a slight body-lift (you mean suspension lift - B ) by just fitting slightly longer shackles at the back and turning up the front torsion bar. A friend of mine did his at the beginning of the year and it cost him the big total of R700.00

Another thing one must find out before fitting larger wheels is if your spare wheel will still fit in the normal place. I know the guys with the 33" tyres cannot carry a spare at the normal place.

[007]

Hi Piet

I'm confidend that the 31" will fit in the space for the spare whell. the reason is that a longrange tank is fitted, and the spare sits below it. The only thing is that the 31" will be wider, creating less ground clearance below the wheel. So I guess that I'll move it in the back

[pietpetoors]

Yes, the guy with the white SFA and 33" Hilux on the pic in the header also had his 33" spare under his extra tank. Until it hit a huge dent into the spare tank. Now he puts it loose on the back or on top of the canopy.

If you do not have a extra tank the 31" still fits in the standard place for the spare wheel.

[007]

I know this is off the subject, but does anyone know where (besides from the dealers) where I can get a chrome tube type or Legend35 rear bumper for the bakkie

[Family_Dog]

I already had the OME suspension lift done on the 2.7i when I then only later fitted the 31" tyres, but I am sure the standard suspension would accommodate the bigger tyres as well, under most conditions.

My 2.7i does not have a LR tank fitted, so I use a 31" spare as well. The SFA however, has a narrower tyre (I forget the size) fitted on to a 16" rim which works well. Overall height is very much the same as my standard tyres on the SFA, but the profile is narrower. I do have a LR tank on the SFA, and fitting a 31" tyre there is problematic as it is far too low for use on a trail.

-F_D

[BenHur]

I know this is off the subject

It is your topic so feel free to go of it. We not that strict about off topic as some other forums

[BenHur]

You can also have a custom tow-bar build with a spare wheel carrier.

Look at this one one the link to give you an idea of how it looks and works.

http://www.backrack.co.za/