Team-BHP - Want to upsize your wheels with lower profile tyres? Read this first

Remember my thread on why cars with low profile tyres tramline a lot more?

At the Sepang track event, I asked someone from the Michelin Motorsports team why race cars don't wear super low profile tyres, while most after-market modified cars seem to sport 19 / 20 inch wheels with tiny sidewalls? Here's what he had to say:

The larger the wheel, the heavier the wheel + tyre combination. This increases unsprung weight, not a good thing
Super low profile tyres actually suffer from poorer grip on bumpier tracks. On an uneven surface, a taller sidewall can absorb bumps, where a low profile tyre would simply deflect. This, in a way, explains the tramlining that I was complaining about in the Vtec. Now, when hurtling down a bumpy Lonavla ghat section, which combination do you think will offer better grip? Which Indian road is perfectly paved again?
Generally, the larger the wheel size, the thicker the available tyre sizes (ever heard of a 195 mm tyre on 17 inch wheels?). Oversized tyres can actually SLOW the car's acceleration times
Some googling on the matter lead me to C&D's test article comparing different wheel & tyre combinations. Surprise surprise, 19 inch wheels with fatter tyres actually had lesser grip than 18s with thinner rubber. And there wasn't any difference in the skidpad rating of 225/45 R17 versus 205/55 R16 sizes! Note that the thinnest tyres recorded the best acceleration times
As is well known, the lower the profile of your tyres, the higher the rate of suspension wear & tear

Of course, a wheel upsize with lowered side profiles lead to sharper steering response and superior grip on flat roads. Within the Indian scenario, most OEM wheel + tyre sizes have smaller wheels + large sidewalls for ride comfort + costs (the smaller the wheel, the lesser its cost). Enthusiasts looking for a better driving experience should definitely upsize their wheels & tyres, but the point of this thread is....we probably shouldn't go overboard.

Most importantly, remember, its the quality of tyre that makes all the difference. A 205 patch high quality compound will inevitably offer you more grip than an average 225 patch tyre.

Summary: Upsize, but don't overdo it. Large (heavier) wheels, super low profile tyres and an ultra-fat contact patch can actually kill performance. Choose a reasonable upsize instead.

Good points GTO. I Perfectly agree with you. Low profile tires are not meant for our road condition. It will only add more bling to the car other than performance. Lesser thick rubber means lesser damping of the vibration, which leads to more strain on struts and less grip on ground. It will surely affect the life span of suspension+the chasis.

But that test report on the Golf is just unbelievable! I always thought fat tyres means more grip. It proves that I was wrong.

I think our Tyre Gurus should make a Upgrade Chart for all cars (Including stock tyre size and the recommended size of upgrade). It would really help people to choose the tyre accordingly and save their money!

Rgds.

Superb thread and very valid observation GTO.

I drove a cousins Esteem who has super low profile tyres(dont recall the specs). He is the ricer types. The car did seemed to have very very stiff ride and very low grip on corners (I now recollect the road was bumpy for sure) inspire of the fact that he has widers tyres. Yes the steering is sharper but unless you get out of the city, you would hardly get an opportunity to utlise the full potential. My lancer with 75 profile tyres handles much better in comparison.

The point 2 you have mentioned is something I can vouch for and have experinced it first hand.

I would upsize a a size or two but anything below profile 45 is something I would stay miles away from. Not to forget the heavy wear and tear and bumpy ride.

vaisakhr: refer to iraghava's post in http://www.team-bhp.com/forum/tyre-a...-your-car.html

Very good point made here GTO. Infact I would like to bring another issue with oversizing.

As brought to my notice by a few people I know, oversizing has lead to faster wear and tear to suspension and allied components that make up the unsprung mass.

Infact most of make a mistake of going more than 1 percent of overall diameter increase or decrease. Even this is detrimental to the parts as they are built to run at a particular tolerance, when we change those tolerances to something that it was not built to do, it will fail.

Quote:

Originally Posted by Gilead

This is true, but cars that come with OE low profile tires will have a much more rigid and hardy suspension as well.

Yes and no.
OE low profiles come in sporty/sports cars which are tuned for performance/spirited driving.

Some vehicles(American SUVs, for example) that are developed to be bling come off the factory with large rims and the factory provides a soft suspension to make up for the hard ride that the 19/20" stock rims will induce.

Quote:

Originally Posted by Gilead

I remember reading a while ago that you had upgraded to 16 or 17 inches on your Civic. You think that was an overkill now? I personally would have gone for wider rubber on 15 inches.

205s are available in 16 and 17. So, you can have your bling but also keep your ride,performance,FE,steering feel, blah blah blah! :)

Quote:

Originally Posted by Gilead (Post 2040413)

This is true, but cars that come with OE low profile tires will have a much more rigid and hardy suspension as well.

What about when someone upsizes and gets really low profile tyres for a regular commuter? Say, a Toyota Altis?

Quote:

I remember reading a while ago that you had upgraded to 16 or 17 inches on your Civic.

Not upgraded yet. A 101.25 mm sidewall (of the 225/45 R17) ain't too bad, though 205 / 215 on 16 inch wheels would give a better ride. What is a strict no-no for the Civic is 18 / 19 inchers (which is the point of this thread).

Good that you put it up, these are basics of tyre upsize. As a thumb rule always stick to +1 or +2 for upsizing on a stock car. Anything above this would require better suspension at the least to perform.

When i did the upsize for Swift i had done a lot of reading up and finally decided on 195's on 14 inch, which was ideal for ride+handling+performance (In Indian conditions). Reference was UK swift owners, though they had 15 inch rims. Anything more will just zap the power from the car or make it bumpy like crazy in India.

Many in India still go for super wide and super low profile, why coz they feel it will perform better and will look better. Which is one sure shot way of screwing up the performance and life of a good vehicle.

When I got my Getz CRDi in 2009 June, one of the first things I did was to upsize to 15" from the stock 14", and go for 195/55 R15 Yoko S.Drives - from the stock 175/65 R14 Goodyears. Spent a tad over 17k for a set of 4 tires then. Within one month of this, my rear right tire ripped on a stone lying precariously on a corner - sidewall went for a toss, and had to replace the tire. Damage: 4350 for changing the tire. After about 1 year, the rear right tire has developed a cut about an inch and half long.

While the tires offered me excellent grip on clean roads (NICE, NH7, etc), the comfort in city / surfaces that were uneven even a bit was nothing to tell - I felt every tiny stone on my bottom, inspite of varying air pressure between 26 PSI and 32 PSI (stock recommended is 30).

So after a year's running on 195/55 R15, I am going change back to 14", albeit with a 185/60.

My suggestion for those who are upsizing: try the way a similar car behaves with your planned size if possible - else you may be in for surprise :)

Quote:

Originally Posted by Jaggu (Post 2040778)

As a thumb rule always stick to +1 or +2 for upsizing on a stock car.

Agreed. However, will add that it varies from car to car. Example : The Punto / Linea sisters come with fat tyres from the factory itself. I wouldn't bother upsizing those. On the other hand, a Chevrolet Beat is horribly under-tyred (155 patch) and requires atleast a 175 / 185 width contact patch.

Quote:

Anything more will just zap the power from the car or make it bumpy like crazy in India.

One of the reasons I put this thread up is a couple of Figo owners getting 195 tyres....that's just plain ridiculous. The car has a mere 68 horses on tap! 185 is the max I'd go with a Figo.

Quote:

Originally Posted by ph03n!x (Post 2040845)

While the tires offered me excellent grip on clean roads (NICE, NH7, etc), the comfort in city / surfaces that were uneven even a bit was nothing to tell - I felt every tiny stone on my bottom, inspite of varying air pressure between 26 PSI and 32 PSI (stock recommended is 30).

So after a year's running on 195/55 R15, I am going change back to 14", albeit with a 185/60.

How about 195s on 14 inch wheels? You'll have your ride quality too. Reason = That Getz CRDi has an awful lot of torque :D

Quote:

My suggestion for those who are upsizing: try the way a similar car behaves with your planned size if possible - else you may be in for surprise :)

Now here's advice worth a million bucks.