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As far as i know , top speed should be better with low profile tyres.
Can someone confirm this.

And my personal opinion says 15" stock alloys painted purple definitely look better than the previous ones

Well , its the width which decreases TOP SPEED , i.e. 225/45 R17 setup decreased the Top Speed , where as the 205/60 R15 did not hamper the top speed . .

And about the Purple painted ALLOYs , theres a small little surprise coming up . . check out this thread soon . . have an update in the alloys . . :)

If the width decreases the top speed , why is it that the lambos and others have tyres
like 235/35ZR19 in the front and 295/30ZR19 ( in the Gallardo)

Wont the width in this case decrease the top speed?

EDIT : Waiting for the update on the alloys ;)

Wider tyres especially the increased rim size means higher drag due to the heavier tyres/wheels & of course the added load due to the increased contact patch.

IMO 225/45 R17 is too wide for a stock Corolla.

Because they have about 500 bhp+ whereas a stock Corolla has 125 bhp. They can get away by using wider tyres since they have the power to use them and also since they're high performance cars, they need the wide rubber to put the power down effectively & also maintain firm grip on the road while takeing turns/curves at insane speeds.

Two different car, two difference purposes. I don't think a comparison between them is correct Abhinav.

Hi guys, very interesting observation :) Karan & iRaghava...

These are not comprehensive or rigorous, but, by switching to a taller tire (~7.3 mm), the torque arm has increased in length, but not by much. The gearing at the contact patch decreases from 3.189 to 3.152, so the drop is very very small (~1.2%).

Coming to aero drag, the section width has increased by 20 mm due to the tire change. Assuming a ground clearance of 16 mm, & even allowing for a Cd of 1.0 (way too high as the tire curves away), the aerodynamic force due to the increased width alone, at a speed of 200 Kmph, is around 1.1 N only.

If you ask me, I don't think increased aero drag due to the wider tires alone can explain the relatively large drop (> 5%) seen in the top speed. The tune of the car could've decreased or other mods (like a body-kit) could be at fault. The rolling resistance could've increased too (although I think stiffer tires have lower rolling resistance values). Other things to consider - the tire pressures could've been lower, or the tread could've been thicker ! :)

The drop is definitely due to 2 reasons

1. increased rolling road friction because of additional width

2. increase in unsprung weight on the drivetrain

These two factors are very much capable of reducing top speed by upto 10%

Bro if you are looking at the Lambo then do keep in mind you are looking at a RWD most importantly and wider tyres to harness the insane amount of BHP and put it on the road. Goes for almost all RWDs with lots of power. Wider rear to put down the power, smaller front tyres to aid handling.
And rightly said by Ishaan the cars being compared are not right as each of them are in their own leagueand made/built for separate purposes.

And guys the ALLOYS are TAIWANESE make , so not the best quality racing alloys which are a lot HEAVIER so that is also one of the major factors for the top speed not goin above 200 .

Another experience i want to share is that with the Stock Setup , and engine under stock conditions just about did a 200 , but when added with the performance mods and checked the top speed (after getting back to 15"s) it did a 210 , where as the top SPEED of A COROLLA is 196 km/h (taking the speedo errors into picture) .

Well , have painted the 17" Chrome Alloys ( minus the spinners ) Purple , and have left the circumfrence CHROME .
They are looking HOT .
Will upload the pic. soon. cheers:

That should be a looker! So switching back to 17s?
Waiting for the pics!

Already have . . will upload the pics by tomorrow .

Sorry for the poor quality image .(was taken when the car was going for wheel alignment and balancing)
Will post better pics. soon .
So is it looking better now ?

Thanks for the info guys

For once i was made to think that Super cars will run faster if on less wider tyres.

@ Ishan
I wasn't actually comparing the rides ( just wanted to know why the sports car have wider tyres when wider tyres lower the speed ( like in karan's corolla)


@ karan
Please put a clearer picture of the alloy
The chrome finishing you have left is looking just too amazing.
nice thought
cheers:
Abhinav

Yes ,much better.!
Looking forward to some better quality pics now.

Thanks , Really busy with college right now , Will post better quality pics. soon .