whitestu
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| posted on 24/9/11 at 09:32 AM |
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How much better are 13" wheels?
I'm planning on replacing the TSW alloys on my car with some TD Pro race 1.2's, but not sure whether to go for 13" or 15".
There isn't much diffference in price for either [wheels or tyres] and the range of tyres in 15" is much bigger.
Is there a real noticable advantage from fitting 13's?
Stu
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gottabedone
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| posted on 24/9/11 at 09:53 AM |
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...................The purists will tell you that you must have 13" and nothing else but I can't see how anyone could drive a car on our
roads with 13" wheels these days - some of the potholes around her are 3-4" deep you'd drive into a hole and not get out
again!
I'd go for tire choice and 15" wheels personally.
Steve
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gottabedone
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| posted on 24/9/11 at 09:54 AM |
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Oh and very nice car buy the way
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Jon Ison
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| posted on 24/9/11 at 10:06 AM |
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You will get a more comfortable ride on 13's and much better handling, mainly due to the higher tyre walls on the 13" tyre, the tyre wall
will flex more and let go much later giving a much better feel of whats happening under your butt than a lower profile 15" tyre.
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mookaloid
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| posted on 24/9/11 at 10:12 AM |
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quote:
Originally posted by gottabedone
...................The purists will tell you that you must have 13" and nothing else but I can't see how anyone could drive a car on our
roads with 13" wheels these days - some of the potholes around her are 3-4" deep you'd drive into a hole and not get out
again!
I'd go for tire choice and 15" wheels personally.
Steve
I think you are missing the point completely. The rolling radius of the wheel tyre combination can be exactly the same for either 15 or 13"
wheels.
if you have 13" wheels then you will lose grip in a more progressive way due to the increased depth of the tyre sidewall - the larger
wheel/lower profile the tyres the more sudden the tyres will let go.
oh and the ride will be better on 13s
cheers
Mark
"That thing you're thinking - it wont be that."
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StevieB
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| posted on 24/9/11 at 10:13 AM |
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I think the overall diameter of the wheel wouldn't be that much different. In fact I think having the smaller diameter wheel and larger profile
tyre helps absorb some of the pot holes we have.
I split the difference on my Indy and had a set of 14" Pro Races. This is mainly because it was a better fit over sierra running gear otherwise
I would have gone for 13". Got them from Demon Tweeks - they were special order to get the ET38 offset.
Tyre choice is fairly limited at 14" though, but they do R888's in this size and that was I wanted.
ETA - damn, beaten to it!
[Edited on 24/9/11 by StevieB]
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MikeRJ
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| posted on 24/9/11 at 10:15 AM |
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quote:
Originally posted by mookaloid
oh and the ride will be better on 13s
cheers
Mark
Exactly, the larger sidewalls soak up way more energy than low profiles tyres, so less stress on suspension if you do hit a pothole as well.
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Mark Allanson
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| posted on 24/9/11 at 10:21 AM |
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I have only had 13" on mine, but have recently gone from 185 60 13's to 185 70 13's, the car feels much quicker now, SOOOO
controllable, predictable - wish I had done it years ago
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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franky
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| posted on 24/9/11 at 10:38 AM |
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it depends on your setup. A car can be made to handle just as well on bigger wheels as long as you're not running a tiny profile tyre.
If 13"'s were the holy grail they'd be fitted on the modern extreme performance cars.
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afj
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| posted on 24/9/11 at 10:52 AM |
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quote:
Originally posted by franky
it depends on your setup. A car can be made to handle just as well on bigger wheels as long as you're not running a tiny profile tyre.
If 13"'s were the holy grail they'd be fitted on the modern extreme performance cars.
They are, f1 wheels are 13 i think
eerrrrrrrrrrrrrrrr
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franky
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| posted on 24/9/11 at 11:00 AM |
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quote:
Originally posted by afj
quote:
Originally posted by franky
it depends on your setup. A car can be made to handle just as well on bigger wheels as long as you're not running a tiny profile tyre.
If 13"'s were the holy grail they'd be fitted on the modern extreme performance cars.
They are, f1 wheels are 13 i think
Adrian Newey said he would fit bigger if regulations allowed. Or look at a race series where you can run what wheel/tyre combo you want.
[Edited on 24/9/11 by franky]
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Mark Allanson
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| posted on 24/9/11 at 11:14 AM |
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quote:
Originally posted by franky
it depends on your setup. A car can be made to handle just as well on bigger wheels as long as you're not running a tiny profile tyre.
If 13"'s were the holy grail they'd be fitted on the modern extreme performance cars.
Modern extreme performance cars don't weigh 600kgs!
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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adithorp
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| posted on 24/9/11 at 11:14 AM |
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quote:
Originally posted by franky
it depends on your setup. A car can be made to handle just as well on bigger wheels as long as you're not running a tiny profile tyre.
If 13"'s were the holy grail they'd be fitted on the modern extreme performance cars.
The larger the sidewall the more compliant the tyre will be, allowing it to deform more due to inperfections in the surface and maintain grip. however
when side forces are applied the higher the sidewall the more the tyre will be distorted sdeways, effecting the contact patch and causing less grip.
As a result the best combination depends on the weight of car they're fitted to; In other words its a compromise. Add to that the fact that
smaller wheels and tyres have a weight advantage the rotating weight is reduced and both exceleration and braking will be improved.
The light weight of a seven (especially a BEC) allows you to get away with running 13" with higher profile tyre. They're not used on
supercars because of the weight of the car increases the side forces when cornering and deforms the sidewall to the point where larger wheels and
lower profile tyres have a handling advantage. the ultimate "extreme performance cars" have to be F1's and at 600kg's they run
13" wheels.
I found my car handled better, was more predictable and more comfortable when I switched to 13".
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Jon Ison
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| posted on 24/9/11 at 11:15 AM |
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Look at a like for like series where you can run what you want, ie 7's.
Ive run both I know which I would fit every time.
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Jon Ison
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| posted on 24/9/11 at 11:25 AM |
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even with higher profile side walls you cant allways keep the rubber on the ground......... 
This same spot at Cadwell I struggled to get airborne on 15's as I couldn't get the grip/drive our of the corner at the bottom of the
mountain as the car was wanting to slide/spin putting the power down whilst still cornering.
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franky
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| posted on 24/9/11 at 11:40 AM |
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quote:
Originally posted by Jon Ison
even with higher profile side walls you cant allways keep the rubber on the ground.........
This same spot at Cadwell I struggled to get airborne on 15's as I couldn't get the grip/drive our of the corner at the bottom of the
mountain as the car was wanting to slide/spin putting the power down whilst still cornering.
Awesome pic! I've been airborne over the mountain on 2 wheels so I bet its good fun on 4.
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britishtrident
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| posted on 24/9/11 at 11:50 AM |
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With 13" wheels and higher aspect raito tyres the wheel is much more like to survive a a blow out or encounter with a pot hole or kerb.
Generally with higher profile 13" tyres the slip angles will be higher for the same later grip but the breakaway more progressive and more
fun to drive close to the limit of adhesion.
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RK
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| posted on 24/9/11 at 12:27 PM |
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Not adding anything really, but I have only done autoslalom on 13's. They are very predictable, but leave the car very low, which is a big
stress when flat towing the car to events. I tore the welded exhaust mounting brackets off the car once (since bolted new brackets to the floor). Not
road legal yet. Wish I'd done 15's to begin with for the simple reason that tyre choice is much larger and clearance. Did anyone notice I
spelled rubber wheel wrong just for you?
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slingshot2000
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| posted on 24/9/11 at 01:07 PM |
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quote:
Originally posted by RK
Did anyone notice I spelled rubber wheel wrong just for you?
If we are going to be this pedantic, you should have written 'spelt', rather than 'spelled' !
Regards
Jon
(edited to remove 'it', thanks for pointing 'it' out, owelly)
[Edited on 24/9/11 by slingshot2000]
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owelly
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| posted on 24/9/11 at 01:16 PM |
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And you have added an extra word Jon.
http://www.ppcmag.co.uk
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whitestu
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| posted on 24/9/11 at 01:28 PM |
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Thanks for the replies.
The RR of 13" on 185/60 13s is very similar to 15" 195/50 15s [which is what I have now]. The 13s are just over 70mm smaller.
On 185/70 13s the RR is bigger and 205/60 13s are pretty much the same as 195/50 15s, so ride height shouldn't be an issue.
Stu
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Bare
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| posted on 24/9/11 at 04:40 PM |
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It's about Unsprung Weight and Rotational Mass.
A smaller rim, even with large sidewall tires... Weighs LESS...than a large rim and thin tire.
And as a rotating mass, significantly less. Far outweighing :-) the claimed advantages of a low to no sidewall tire.
Again the F1 example.. where performance is Everything.
Sad truth is: Tall rims and skinny tires are all about posing, not performance
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indykid
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| posted on 24/9/11 at 05:02 PM |
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Small rims also limit the size of brakes and uprights.
When you have a tonne and a half of supercar travelling at 200mph, try get sufficient brakes in a 13" wheel...and then get the wishbones to
react the torque on a tiny upright.
Each suit an application
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David Jenkins
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| posted on 24/9/11 at 05:55 PM |
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I have 185x70 on 13" rims - I have always found them to be totally predictable, and they do cushion you from bad potholes. I'm sure that
bigger wheels and lower-profile tyres will give you better cornering - but my wheels & tyres give me plenty of notice when they're about to
let go, resulting in a nice controllable slide rather than a sudden "oh sh*t" moment.
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britishtrident
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| posted on 24/9/11 at 06:03 PM |
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quote:
Originally posted by Bare
It's about Unsprung Weight and Rotational Mass.
A smaller rim, even with large sidewall tires... Weighs LESS...than a large rim and thin tire.
And as a rotating mass, significantly less. Far outweighing :-) the claimed advantages of a low to no sidewall tire.
Again the F1 example.. where performance is Everything.
Sad truth is: Tall rims and skinny tires are all about posing, not performance
Depends what wheel and tyre some 15" rims weigh a proverbial ton because they are engineered to carry big heavy saloons same goes for
tyres.
In F1 13" inch rims are used mainly because they give most of the suspension movement and 13" rims have been used in F1 since the
1964 season when they replace 15"
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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