Wider wheels and performance

blacklineninja

Track Warrior
Points
162
So I'm well aware that fitting larger diameter wheels to your car can slow it down some, but what if you stick to the same diameter but go 2 inches wider? I know there will be some wheel arch work needed, but how would those extra 2 inches affect performance and handling, especially when combined with a 30-40mm static drop on Koni STR-T's?
 

blacklineninja

Track Warrior
Points
162
just for completeness, the offset is also different, going from et43 to et15, the 1010tires calculator says i gain 3mm of internal clearance, but stick out a further 53mm
 

HugoBoss

The Torque Meister
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77
Location
Australia NSW
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r33 skyline gtst
Hey buddy, I can almost assure you the fuel consumption will increase to a degree. The handling will certainly be affected just couldn't say good or bad or by how much. And yes there is defo's going to be some guard work required. For DIY I recommend a guard roller and be sure to use a heat gun to warm any surfaces about to be rolled.
 

obi_waynne

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A3 1.4 TFSI 150 COD
Welcome back buddy, long time no speak.

You'd need to get the camber and toe setup again as wider wheels will almost certainly push this out of the ideal.

More rubber on the road can mean more grip in the dry but less grip in the wet! The larger surface area reduces the pressure exerted on the road.

Don't expect phenomenal or even noticeable improvements in handling other than what you'd get by fitting a new set of tyres.

What are your aims here, better cornering? More grip or mainly for aesthetic reasons?
 

TCJBOLDIE

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2011 Honda FN2
Just fit lower profile tyres to larger wheels so the rolling diameter is the same as the stock wheel/tyre combo to keep the speedo correct.
The reason that wider tyres can have less grip in the wet is that they have to displace more water so it can lead to loss of road contact in extreme cases due to a wedge of water building up in front of the tyre.
 

blacklineninja

Track Warrior
Points
162
Thanks guys, appreciate this. I mainly want to make my car more aesthetically pleasing. Given that i spend 80% of my time in rush hour traffic, AND it being a 1.3 litre diesel FIAT there seems little point spending money on making it a BIT faster. I would however like to improve handling and looks so that's the main motivation and why I'd prefer to stick with the same daimeter wheels, although i would consider 16's with low profile rims... If i can find some i like
 

TCJBOLDIE

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Thanks guys, appreciate this. I mainly want to make my car more aesthetically pleasing. Given that i spend 80% of my time in rush hour traffic, AND it being a 1.3 litre diesel FIAT there seems little point spending money on making it a BIT faster. I would however like to improve handling and looks so that's the main motivation and why I'd prefer to stick with the same daimeter wheels, although i would consider 16's with low profile rims... If i can find some i like

I think you meant to say " 16s with low profile tyres ":bigsmile:
 

blacklineninja

Track Warrior
Points
162
Err, yeah, that’s the one…

Right, so I’ve baked my noodle trying to work this out, but I think I’ve almost cracked it…

Standard, I've got 6x15" ET43 rims wearing 185/65 R15 88T's. T is 118mph rated, faster than Bella will ever go without being driven off a cliff :amazed:

New rims I've seen are 7 x 15" ET40 rims - the 1010Tires Offset Calculator makes that 10mm less internal clearance and 16mm outward extension. On another forum it says that the Grande Punto can take wheels with offsets between ET35 and ET45 and several big-name alloy wheel retailers list these wheels as fitting my car, so that should be all good right? The manufacturer stated weights would appear to be a bit lower than standard, should that help keep acceleration at the same level and keep my speedo accurate?

I also want some lower profile tyres - not crazy Hella-thin profile, just a bit sportier-looking cos my sidewalls are HUGE – 120.25mm by my calculations (185 / 100 = 1.85 x 65 = 120.25??).

The ideal would be improved drivability, but I’ll settle for exactly the same or not noticeably different, obviously I’ll have to take slow bumps even slower and annoy a few peeps, but revenge, cold dish, etc.

I've got my eye on Falken ZE914's. 205/55/R15 are the smallest option that match the load index and speed rating - 88V (149mph, Bella might crumble) sidewall size would be 112.75mm... not that much smaller really, but I want to be safe and keep my car actually, y’know, drivable? So these should be the puppies no?

So with a static suspension drop of 35mm on some Koni STR.T’s and an additional 7.5mm my car will be a frankly whopping 42.5mm lower. What do we think? Sensible or a disaster waiting to happen?
 

obi_waynne

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A3 1.4 TFSI 150 COD
Using our wheel size calculator http://www.torquecars.com/tuning/alloy-wheels.php

Current 310.75mm rolling radius 1952.5mm circumference
New 303.25mm 1905.37mm circumference

So the new wheels have a 47.12mm smaller circumference so you speedo will be underreading a little. This actually sounds like a sensible proposition but it does seem like a massive drop for a diesel engined car. Personally I'd stick with a 20-30mm drop if you must drop but ask other owners what they've done and you might find it's perfectly ok on this model.
 

old-git

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Location
Essex
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Elan & Robin Hood
Depends on the context. Most men would like an extra inch..........on the width..........................of their tyres.

Assuming there are no rubbing issues then an inch shouldn't cause any problems with tracking and bearing wear, but it's good practice to get the tracking checked anyway when fitting new tyres.
 

TCJBOLDIE

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2011 Honda FN2
LOL OG love your play on words.
I have changed from 205/70/15 to 225/45/17 and the rolling diameter is almost spot on equal so speedo is fine
 

obi_waynne

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The new tyre ratings make it easy to compare tyre features. My priorities are grip and we weather breaking! Forget the economy ratings & noise readings.
 

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