[naj]

Kpzen Sir,
Good day to you.
Thank you for explaining the tyre terminology with calculations.All doubts cleared.

Also can you please tell me by how much one can increase the rim size say from 13 inch to 14 to 15 taking into account that the tyres wont touch the wheel arches ?How to decide on that and gain max ground clearance for a given car.

Naj

[tsk1979]

Naj, this link has a handy calculator.
You can also use the article in advice section
Car Bibles : The Wheel and Tyre Bible Page 1 of 2

[sushrutha]

Stock Tire - 175/70R13 -------------Tire 1 - 175/65R14
Section Width: 6.88 in 175 mm ----Section Width: 6.88 in 175 mm

Rim Diameter: 13 in 330.2 mm ----Rim Diameter: 14 in 355.6 mm

Rim Width Range: 4.5 - 6 in ----Rim Width Range: 4.5 - 6 in

Overall Diameter: 22.64 in 575.05 mm ----Overall Diameter: 22.95 in 582.93 mm

Sidewall Height: 4.82 in 122.42 mm ----Sidewall Height: 4.47 in 113.53 mm

Radius: 11.32 in 287.52 mm ----Radius: 11.47 in 291.33 mm

Circumference: 71.12 in 1806.4 mm ----Circumference: 72.09 in 1831.0 mm

Revs per Mile: 918.7 ----Revs per Mile: 906.3

Actual Speed: 60 mph 100 km/h ----Speedometer1: 59.1 mph 98.6 km/h

Speedometer Difference: - Speedometer Difference: 1.368% too slow
Diameter Difference: - Diameter Difference: 1.36%
courtesy
Tire Size Calculator - tire & wheel plus sizing

[dharmana]

I got a Maruti SX4 Zxi recently. I don't like the high ground clearance(ride height) and want to lower the suspension a little bit(around 15mm) to make the car look more aggressive and sporty. I want to know if lowering kits are available in India or if not where do I need to go to get it done. Something like shorter suspension springs etc would be fine. I know I can decrease the ground clearance a bit by using low profile tyres but I want to lower the ride height by reducing the wheel well height. I would like to know if any sport suspension kits like lowering springs and matching shock absorbers are available in India and also if they are specific to the car model you own. Any names of reputed brands available in India would be a help.
For example the SX4 Sedan which was launched in America uses sport suspensions to bring the ride height down by around 10mm compared to the SX4 crossover which sits a little higher than the sedan. Any decrease in ground clearance of 10-25mm would be commendable as I might further lower the car in the future by going for lower profile tyres. Also does anyone know if this is a simple job which can be done in any automotive garage shop or if this is a complicated process and is done in only big cities like Bangalore, Chennai etc?

[itwasntme]

Check with BHPian Turboindia (Peter) or at Pete's Automotive Products Pvt Limited

He maybe able to help.

[Ram]

Suspension lowering is merely an word-of-mouth term for it, dharmana!

It is no doubt a complicated process. And it comes with a high probability of writing-off the design and relegating a worthy car to the wild and wacky thread!

Granted there are east Los Angeles low-rider clubs that tinker with this sort of thing, but bear in mind ...

...that they use bolt-on, factory-made, after-market components that have gone through rigorous engineering design by real automobile/aircraft designers.
Often, these are designed to exceed the specifications of the OEM components they are substituting.

And the base platforms modded by these clubs are strong X-frame 1963-67 rear-wheel-drive Chevrolet Impalas -- not bottom of the food-chain Japanese econoboxes, which were never purposed for longevity, anyway!

In the process details are:
Detailed study of the engineering drawings -- the tolerances -- suspension travel -- danger of bottoming out -- fabrication of custom suspension components -- guarantees, to handle the stresses you will put on the crate -- okaying by regulatory bodies ...

A very good strategy for you could be to import the lowering kit meant for the Suzuki SX4 sedan (USA or Canadian version).

You have to work with a qualified professional (let's call him an automotive architect) who designs cars for a living. Very few such people are found in India, to the best of my knowledge and will be fairly expensive.

They will have access to a great deal of expensive equipment, and a very well equipped factory with static and dynamic measurement instruments.

Your expenses can end up, somewhat more than simply importing a readymade production-line Corvette or Porsche or Italian sports job, for instance.

Beware of desi cosmetic modifiers (so called screwdriver street mechanics) who can't even take accurate measurements, nor make drawings worthy of marks in a qualified professor's scrutiny, leave alone handle automotive design software. They are invariably mentally-challenged as far as appreciating the safety and handling consequences of their tinkering.

Bear in mind that the final outcome may not pass professional inspection.

It's the difference between going to a super-specialty cardiac surgeon and going to a beachside masseur or witch-doctor, for crying out loud.

Ram

[harsha.cs1]

I am surprised that someone using Indian roads wants lower ground clearance! I would suggest you thank your stars that your car has a relatively higher GC and retain it, rather than risk your car for mere cosmetic reasons!

Originally Posted by dharmana

I got a Maruti SX4 Zxi recently. I don't like the high ground clearance(ride height) and want to lower the suspension a little bit(around 15mm) to make the car look more aggressive and sporty. I want to know if lowering kits are available in India or if not where do I need to go to get it done. Something like shorter suspension springs etc would be fine. I know I can decrease the ground clearance a bit by using low profile tyres but I want to lower the ride height by reducing the wheel well height. I would like to know if any sport suspension kits like lowering springs and matching shock absorbers are available in India and also if they are specific to the car model you own. Any names of reputed brands available in India would be a help.
For example the SX4 Sedan which was launched in America uses sport suspensions to bring the ride height down by around 10mm compared to the SX4 crossover which sits a little higher than the sedan. Any decrease in ground clearance of 10-25mm would be commendable as I might further lower the car in the future by going for lower profile tyres. Also does anyone know if this is a simple job which can be done in any automotive garage shop or if this is a complicated process and is done in only big cities like Bangalore, Chennai etc?

[shankar.balan]

Quite simply, this is a bad idea according to me.
the alarming condition of our Indian roads with a high incidence of speed breakers, pot holes and other uneven surfaces, will ensure the car will quite literally bottom out every time you take a drive, if you go for a modification of this kind. Frankly if you really wanted such a low GC then why did you bother buying an SX4? You could have bought the Civic instead!

Originally Posted by dharmana

I got a Maruti SX4 Zxi recently. I don't like the high ground clearance(ride height) and want to lower the suspension a little bit(around 15mm) to make the car look more aggressive and sporty. I want to know if lowering kits are available in India or if not where do I need to go to get it done. Something like shorter suspension springs etc would be fine. I know I can decrease the ground clearance a bit by using low profile tyres but I want to lower the ride height by reducing the wheel well height. I would like to know if any sport suspension kits like lowering springs and matching shock absorbers are available in India and also if they are specific to the car model you own. Any names of reputed brands available in India would be a help.
For example the SX4 Sedan which was launched in America uses sport suspensions to bring the ride height down by around 10mm compared to the SX4 crossover which sits a little higher than the sedan. Any decrease in ground clearance of 10-25mm would be commendable as I might further lower the car in the future by going for lower profile tyres. Also does anyone know if this is a simple job which can be done in any automotive garage shop or if this is a complicated process and is done in only big cities like Bangalore, Chennai etc?

[tj123]

Originally Posted by sushrutha

Stock Tire - 175/70R13 -------------Tire 1 - 175/65R14

Circumference: 71.12 in 1806.4 mm ----Circumference: 72.09 in 1831.0 mm

Revs per Mile: 918.7 ----Revs per Mile: 906.3

Actual Speed: 60 mph 100 km/h ----Speedometer1: 59.1 mph 98.6 km/h

Speedometer Difference: - Speedometer Difference: 1.368% too slow
Diameter Difference: - Diameter Difference: 1.36%
courtesy
Tire Size Calculator - tire & wheel plus sizing

Adding to what Sushrutha
It is not just a question of improving ground clearance there are some other things happen if you change the tyre size.
The major draw back which occurs and majority of the people won’t even notice is that it will lead to a speedometer error as the speedo gears are calibrated as per the wheel size.

From a purely geometric perspective, changing the tyre diameter could effect the "Perceived Mileage" - assuming the odometer (and speedometer) tabulates the revolutions (RPMs for the speedometer), the traveled distance would be greater than the measured distance if the tire size was increased.

To make it simple your speedometer expects the car to go a certain distance for each revolution of the tire. Imagine: If the tyre is big, the car will go a little further with each revolution. (Your speedometer readings will change with new tyre vs old!)

Thus calculating the FE figures will have errors unless the odometer/speedometer are re-calibrated..

A friend of mine in US was once pulled over for exceeding the speed limit recently as he had put larger tyres than stock on his vehicle. His speedometer measured his speed below speed limits, but his actual speed was much higher.

This error does not "change your actual mileage figures", rather it just gives an erroneous value if you are using your odometer readings to calculate FE.

[GTO]

Originally Posted by tj123

This error does not "change your actual mileage figures", rather it just gives an erroneous value if you are using your odometer readings to calculate FE.

Don't mean to get picky, but larger tyres can sometimes lead to better fuel efficiency. Say you increase the diameter, that results in taller gearing and thus, when you are cruising on the highway at 120 kph, the engine will be ticking over at a lower rpm than on a smaller dia wheel + tyre combo.

Note : I do NOT recommend this unless you really know what you are doing.

[tj123]

Agreed GTO that mileage will increase marginally on highway cruising.
However in city drives mileage will drop as larger dia wheels will require lot more torque to get moving.


In stop-go situation you tend to put lot of extra strain on engine and transmission. Leading to higher wear & tear.

[harsha.cs1]

great point on the extra torque needed in city. agree with TJ.

Originally Posted by tj123

Agreed GTO that mileage will increase marginally on highway cruising.
However in city drives mileage will drop as larger dia wheels will require lot more torque to get moving.


In stop-go situation you tend to put lot of extra strain on engine and transmission. Leading to higher wear & tear.

[rpmx1000]

I watch cars and I mean I watch them!Every time I see a new car coming out, I check what's the ground clearance , and I think that's a factor for selecting a car. I know this sounds strange , but with our roads or lack of them, I think only SUVs are really good for India. So my picture of an Ideal car would be an SUV or a crossover .All said and done there were some discussions about launching an Indigo Advent sometime in 2006 in these forums , but this never saw the light of day. I wonder why?

I'd like to hear views on whether ground clearance really matters or is it just psychological. After all so many times there are large granite stone blocks fallen off construction lorries especially in Bangalore and sometimes these are used to "isolate" vehicles in an emergency (alongwith a friendly neighbourhood twig from a nearby tree) and sometimes a glowing indicator as well as an emergency triangle!!) and once I've done a superman jump from my dad's scooter when I was young on hitting a stone at 30 kmph , and a few months back my dear car's underside brushed against another of the aforementioned stones thankfully without much damage.

But each time I see one I feel I need an SUV - then every time I check the Scorpio prices they zoom northward (Although they have come down of late, I still feel this SUV's too costly ) maybe its the lure of the forbidden fruit that makes so many Indians go for scorpios.

Enough rambling. I'll let fellow BHPians educate me about how much does "Ground clearance" really matter when going to choose a car (is there too much choice ?) or an SUV.

<Ears wide open>
Have fun,
rpmx1000

[triedeverything]

Didn't know where else to ask this question. But what is the 'official' ground clearance of the Scorpio? It is not mentioned on their site.

[fiery enzyme]

Though the profile reduces, the diameter of the wheel increases. So in effect you are increasing the clearance.