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How much better are 13" wheels?
whitestu - 24/9/11 at 09:32 AM

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

gottabedone - 24/9/11 at 09:53 AM

...................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

gottabedone - 24/9/11 at 09:54 AM

Oh and very nice car buy the way

Jon Ison - 24/9/11 at 10:06 AM

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.

mookaloid - 24/9/11 at 10:12 AM

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

StevieB - 24/9/11 at 10:13 AM

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]

MikeRJ - 24/9/11 at 10:15 AM

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.

Mark Allanson - 24/9/11 at 10:21 AM

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

franky - 24/9/11 at 10:38 AM

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.

afj - 24/9/11 at 10:52 AM

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

franky - 24/9/11 at 11:00 AM

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]

Mark Allanson - 24/9/11 at 11:14 AM

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!

adithorp - 24/9/11 at 11:14 AM

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".

Jon Ison - 24/9/11 at 11:15 AM

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.

Jon Ison - 24/9/11 at 11:25 AM

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.


franky - 24/9/11 at 11:40 AM

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.

britishtrident - 24/9/11 at 11:50 AM

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.

RK - 24/9/11 at 12:27 PM

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?

slingshot2000 - 24/9/11 at 01:07 PM

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]

owelly - 24/9/11 at 01:16 PM

And you have added an extra word Jon.

whitestu - 24/9/11 at 01:28 PM

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

Bare - 24/9/11 at 04:40 PM

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

indykid - 24/9/11 at 05:02 PM

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

David Jenkins - 24/9/11 at 05:55 PM

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.

britishtrident - 24/9/11 at 06:03 PM

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"

alistairolsen - 24/9/11 at 08:41 PM

13 inch rims arent used for performance in F1, theyre used because the rules dictate it!

High sidewall tyres arent a good answer, but necessary because no tyres are made for little lightweight cars.

In many cases larger wheels are driven by larger brakes and nothing else.

If yoy look at any race championship with freedom on wheel sizes they will be large, low profile and extremely light to house the biggest brakes possible and have low profile tyres. The lower profile is less forgiving but acceptable in a race car.

scutter - 25/9/11 at 09:20 AM

Stu, After swapping to 13" rims, my car feels a lot better. Ride and avaliable secondhand race tyres also swing it in that direction.

ATB Dan.

coozer - 25/9/11 at 10:07 AM

I'll let you know after I get the 13,s to fit!

Jon Ison - 25/9/11 at 11:18 AM

quote:
Originally posted by alistairolsen
13 inch rims arent used for performance in F1, theyre used because the rules dictate it!

High sidewall tyres arent a good answer, but necessary because no tyres are made for little lightweight cars.

In many cases larger wheels are driven by larger brakes and nothing else.

If you look at any race championship with freedom on wheel sizes they will be large, low profile and extremely light to house the biggest brakes possible and have low profile tyres. The lower profile is less forgiving but acceptable in a race car.


Your missing the point slightly though , we are talking 7 type cars here, most are over-braked already with no need for all singing and dancing super duper huge brakes, most brakes on a 7 struggle to get up to optimum operating temperature, when was the last time you saw a 7 come off track with smoke coming form the brakes because there so hot ? Ive yet to come across brake fade even after 1 hour non stop runs.

I wouldn't run a 1000kg + track car on 13's, I also wouldn't run a 500kg 7 on 15's with low profile tyres.

All imho of course.

alistairolsen - 25/9/11 at 12:27 PM

quote:
Originally posted by Jon Ison
quote:
Originally posted by alistairolsen
13 inch rims arent used for performance in F1, theyre used because the rules dictate it!

High sidewall tyres arent a good answer, but necessary because no tyres are made for little lightweight cars.

In many cases larger wheels are driven by larger brakes and nothing else.

If you look at any race championship with freedom on wheel sizes they will be large, low profile and extremely light to house the biggest brakes possible and have low profile tyres. The lower profile is less forgiving but acceptable in a race car.


Your missing the point slightly though , we are talking 7 type cars here, most are over-braked already with no need for all singing and dancing super duper huge brakes, most brakes on a 7 struggle to get up to optimum operating temperature, when was the last time you saw a 7 come off track with smoke coming form the brakes because there so hot ? Ive yet to come across brake fade even after 1 hour non stop runs.

I wouldn't run a 1000kg + track car on 13's, I also wouldn't run a 500kg 7 on 15's with low profile tyres.

All imho of course.


You're missing my point

on a seven, I intend to run 13s, because there are commonly available secondhand slicks and because I dont need huge brakes etc and because as a light car, high sidewalls are beneficial.

What Im disagreeing with is people suggesting they are the ultimate in performance and low profile tyres are pointless and specifically quoting F1 as an example, all of which is clearly tosh!

The use of high sidewall 13s on seven type cars is a very application specific compromise!

Jos Fury - 26/9/11 at 08:36 AM

I switched from 6x14 185 60 14 superlites, to 6x13 175 70 13 revolutions.
on the scales, the revo was 2 kg lighter. incl. tyre 2,5 kg.
(also saved 7kg in total on front brakes when switching to wilwood powerlites)
car feels more comfy and better handling, more predictable although I haven't drivin that much after the wheel swap

[Edited on 26/9/11 by Jos Fury]

britishtrident - 26/9/11 at 10:49 AM

quote:
Originally posted by alistairolsen
13 inch rims arent used for performance in F1, theyre used because the rules dictate it!

High sidewall tyres arent a good answer, but necessary because no tyres are made for little lightweight cars.

In many cases larger wheels are driven by larger brakes and nothing else.

If yoy look at any race championship with freedom on wheel sizes they will be large, low profile and extremely light to house the biggest brakes possible and have low profile tyres. The lower profile is less forgiving but acceptable in a race car.


Yes with a racing slick breakaway characteristic is more controlled by compound than anything else

Neville Jones - 26/9/11 at 11:17 AM

quote:
Originally posted by britishtrident


Yes with a racing slick breakaway characteristic is more controlled by compound than anything else


Breakaway is more to do with tyre construction than compound. The construction dictates how the tread(slick) compound reacts with the road. Crossplys will be very different to radials.

Put the smallest wheel on that you can get away with, and then the lightest tyre, if performance is the end goal. For the road, like Mark Allanson and a couple of others have put, you just can't better a good 13" wheel with a sensible less low profile will keep you comfortable and on the road in all weathers.

Winter is coming. Watch for the BEC's going off the road on their 15"+ wheels with silly ultra low profile tyres, all suspended on ridiculously high rate springs. There's a few every year.

Cheers,
Nev.

imp paul - 26/9/11 at 12:52 PM

i just got these 13 wheel porn very rare rims Description
Description

[Edited on 26/9/11 by imp paul]

whitestu - 26/9/11 at 02:34 PM

Thanks for all the replies - it was real world experience of switching to 13s that I was after [though the theory is good as well], which given what has been said backs up my thoughts that 13s are definately worth going for.


Stu