from 16" to 13" wheels

[Richard J Darnell]

the "new and cheap minilite" wheels thread on the for sale section has prompted me to replace my 16" wheels with 13" wheels

 

I have never driven a car with 13" wheels so I am relying on the general consensus that this switch will improve the handling.

I assume the grip will also improve if I fit some more exotic rubber (the 16" wheels have Michelin Pilots which most people seem to say is not a good choice)

 

my questions are:

1. am i doing the right thing! ie. please reassure me that the handling will be better (my car is a '98 de dion 1.6k SS)

2. what size wheels? From previous threads I think the best size would be 6 X 13 all round.

3. will ground clearance be a problem? I was intending to fit fairly high profile tyres to help with this but by how much can i expect the ride height to drop (I have non-adjustable springs)?

4. what size tyes (both width and profile) make the best sense for mainly road use?

5. is there anything else to think about eg. will the speedo be less accurate?

 

Edited by - Richard J Darnell on 11 Aug 2001 07:53:43

[mav]

Richard,

 

If you are changing your wheels, please let me know via e-mail if you plan to sell the 16" jobbies. I'm looking to purchase a spare set for my SV.

 

Cheers,

 

Martin

 

Edited by - mav on 11 Aug 2001 09:06:38

[Robin Renton]

I used to have an HPC with 16" wheels & Pilots which looked terrific IMO, but tramlined dreadfully and didn't do anything for the handling - a change to 13" on a sprint day improved things immensely, although the handling was still not right on that particular car!

I now have a K series with 13" wheels and 021Rs and this car is in a different league as far as ride, handling and predictability are concerned. I think that 021Rs are fine for general road use and they are very good value.

The width of rim you choose should be dependant on the power output of the car- wide rims don't always do anything for the driving experience. A 1.6SS is probably best with 6 x 13".

I've had no problems with ground clearance.

I don't think the speedo accuracy is up to much anyway, but check the archives because there was a thread on this a while back.

Robin.

[Drumster]

Richard, I went from 15" Prisoner wheels with 195/50/15 Michelin Pilots to 13" Superlites and Yoko 21Rs 185/70/13. This meant that I could keep the reide height identical (I also have non-adjustable springs) and improve the car's overall handling at the same time. Another reason for the 70 profile tyre is that George Polley Motorsport sells them at a large discount £40 incl. VAT.

Hope this helps.

 

 

Chris Alston

 

Se7ening - it's all miles and smile.gifsmile.gifsmile.gif

1800 x/flow - Loud and Proud teeth.gif

[Graham Perry]

Having been on this forum a couple of years I cannot honestly remember anyone saying that their car was worse for the change. Its one of those things, that where you have to trust everyone elses judgement . 13 inch wheels with 21r's will really surprise you with the grip compared to what you have currently.

[murph7355]

1) Yes. Definitely. Don't worry.

 

2) For the spec. car you have, yes 6x13s are perfectly fine. Also handy if you want to carry a spare (different sizes being a problem here).

 

3) No. You have to be careful over speed bumps but in my experience you do in a K-series car no matter what wheels you have (unless someone has a "BigFoot 7"?). Other than that, don't worry (mine's on 13"s with 60 profile tyres and I've not had any problems).

 

You can work out the differences. I think the equations go something like:

 

16" wheels with 195/50/16 tyres have a radius of 8" + 3.8" (for the tyre sidewall), so 11.8" from the hub to the floor.

 

13" wheels with 185/60/13 tyres have a radius of 6.5" + 4.4" (for the sidewall), so 10.9" from the hub to the floor.

 

So you lose about 0.9" (just over 2cms), assuming the profiles and widths of the tyres are spot on. Tyre manufacturers often have true tyre diameters on their sites.

 

4) 185/60/13 all round should work well for you. You'll probably notice a marked increase in ride comfort (if the profile is increased over your 16" tyres) as well as better handling too (more sidewall gives more "cushioning").

 

You could go for 70 profiles which are a fair bit cheaper (20% or 10 quid a corner or so in the case of Yoko 21Rs) and would give even more "cushioning", but I've never tried these. They would also reduce the ride height deficit over 16"s to about 0.5cms.

 

I'd expect they might give too much sidewall flex, but maybe not.

 

5) Speedo accuracy will change, but I can't remeber if it improves or not! Caterham speedos are notoriously crap anyway. If you're really worried about, fit a cycle speedo which will be configurable for wheel size and will be the most accurate solution you can sensibly get.

 

 

If you keep hold of the 16" wheels you have, in the very unlikely event you don't like the change you can alwasy swap back. And there's a very healthy 2nd hand market for 13" wheels and tyres so I'm sure you'd get your money back.

 

Good luck with it, and don't worry.

 

PS Consider getting the adjustable platforms fitted. It's another relatively cheap way of improving the handling...

[Richard J Darnell]

thanks for all the replies

 

Andy, my current tyres are 205/45/16.

If I switch to 185/60/13 won't I lose a fair bit of grip? (although I assume the switch from Michelins to Yokos or similar will help overcome this)

What is the widest tyre you can fit to 6x13 wheels?

My understanding is that 185/60 on the front is a good thing (I find the steering with my 16" wheels quite heavy) but I prefer the look of wider tyres.

[murph7355]

If you have a std. 1600SS (138ish bhp) I'd say you've probably got too much tyre as it stands, certainly on the front. I would imagine getting the car controllable on the throttle would be quite tricky as there's going to be more grip than power, and as you note the steering is going to be heavy.

 

A switch to less tyre will lighten the whole thing up and the smaller wheel/tyre combination will make the whole thing much more direct and alive.

 

With less rubber on the back you'll probably find you can get the rear of the car out very progressively too (a good thing for the fun factor).

 

You're also correct about the Michelins having much less grip "per inch" than something like a Yoko. I hate Michelin tyres on a 7!

 

On the aesthetics front, surely this is mainly important for those outside the car. Not where you'll be most of the time smile.gif. Also, the 13" wheels will change the whole "theme" of the car...I think the smaller wheels make the 7 look much more race car like and functional. Whilst it's a subjective area I think the 16"s make the car look too over "wheeled".

 

If I were you I'd try it with 185s all round first (I had this on a non-SL 1400 Supersport and it was fine), or if you're really keen to preserve the wide wheeled look maybe go with 205s on the rear (I think these will squeeze onto 6" rims). But definitely go with 185s on the front.

[Stuart Wallace]

Richard,

 

I changed my 16" wheels to 13" with Yoko 32s about 2 months ago. The ride and handing was transformed, I would not go back to the 16s. I was recommended to go for 6" wide all round with 185s on the front and 205s on the rear (I have a Swindon 225 HPC), I was told that this would give the most neutral handing. However for me the car has to look right and the 185s under the flared wings did not, so I tried 205s all round with 6" front and 7" rear wheels. This not only looked right but gave me the same ride height (the Yoko 032s are 60 profile tyres) as my 205/45 16s, the diameter is as near as damit the same. The steering is also much lighter than with the old combination. It might well be that 13X6 wheels with 185s front and 205s are best all round and I would have gone for them if I had cycle front wings. I am delighted with the feel and the look of my new wheels and tyres and I would recommend the change.

 

[murph7355]

Don't forget that fitting different sizes front and rear screws the spare situation. Even more so if you end up going with 32Rs which are asymmetrical.

 

I'm not saying you shouldn't do this (I have after all), but if you do you may as well ditch the spare altogether and carry Tyre Weld (saves even more weight anyway, and in a fair few years of 7 ownership I've yet to have a puncture).

[Steve Campbell]

Go for it.

 

I've got 13" Yoko 32's 185/60 on a standard 1.6k ss .... smile.gif. The look of the car will take some getting used to as the 13's don't fill the rear arches as per the 16's. I thought about going from 13's to 16's (the car already had 13's when I bought it) and didn't find one person who said that would be a good idea !!

 

As for the asymetrical tyres, someone told me that it would make little difference putting one on the wrong way except in the wet (due to the tread pattern & dispersal of water). As a spare is to get you out of a tricky situation 'once in a blue moon' I don't think it would matter.

 

Can anyone confirm the use of the Yoko 32's "backwards" ?

 

 

Steve Campbell

P889 GRR

[Richard J Darnell]

One last question (or questions!).....

If, for reasons of cost, I decide not to buy 13" wheels (and I do like the look of the 16" wheels) what tyres would people recommend?

Are they much more expensive than tyres for 13" wheels?

Is it possible to fit a narrower tyre to a 16" wheel (narrower than 205/45) to lighten the steering at the front? - if so, would this be sensible half-way house solution?

 

Chances are, I will buy the 13" wheels, but answers to the above would help make up my mind.

[Warren S Smith]

I have fitted Yoko A539 to my 16" wheels. It's to early to comment how good they are but they are cheaper (and better) than the offerings from Michelin or Avon.

[old captain slow]

For what it's worth, my car handled really evily after I changed from 16" to 13". Tended to flip into oversteer at the slightest provocation. All it needed was a slightly stiffer front end 5/8 arb plus 170 lb springs did the trick, although I bet not everyone would agree with that combination. Also the adjustable ride height was essential as the car kept clouting the deck on the standard Caterham fixed settings that came with the original HPC wheels.

 

The difference is amazing - go for it.

 

My speedo reads about 5% optimistic compared to GPS readings. 110 indicated = about 105 actual. Seems to be about flat out in my 1.6K SS with flares and windscreen although there is probably a tiny bit left as it only indicates about 6500 in 6th at that speed.

[Delberts Wallet]

If changing from 15/16" wheels do you need to change the cycle wings and stays to suit??

[mike ashurst]

Richard,

 

I was awkward and went from 13" to 16" for road use purely because I wanted more clearance. With the standard Caterham suspension set up on my 1.6K SS I had about an inch and a half under my sump, and clouted it several times (slowly fortunately) on speed humps in car parks and once on the footpath driving into my mates drive. The 16's gave me an extra inch and a bit with 205's on, but the handling has gone downhill. It tramlines, the steering is heavy and it's a much harder ride. My 13's had Yoko 021R's on and were 3/4 worn when I changed wheels after 3500 miles, but the general feel and handling of them was far superior. Overall I'd agree with everything Andy Murphy says.

 

Gareth

 

You don't need to change the cycle wings/stays when going from 16 to 13, althought the wings are slightly smaller on 13's, but you do have to change the stays when going up from 13 to 16 as otherwise they will catch the tyres.

 

Mav

 

Might be tempted to flog my 16's if you're really keen to go that way, as I'm probably going back to the 13's.

 

Mike

[paul.davis]

I aked the same question when James Whiting built my 3rd car (with cycle wings). No question 13" is the way to go for handling and looks are fine. I have used 13" for road and track for 6 years firstly with Yoko 21Rs 60 profile - excellent - but as my track speeds increased I went for Yoko 32Rs to prevent meltdown - Then ACB10s with less camber and now slicks - all 13 inch. I have never had an insurmountable clearance problem - and I have a heavier zetec with lower sump than K series - just needs a bit of thought on narrow cambered bumpy country lanes, gate stops and sleeping policemen. (You may try to get a good deal with tyres already fitted to Minator wheels from Caterham . . . . ??)

 

You will not believe the difference and guarantee no regrets . . .

 

Paul "T" Davis

[Nick VVC]

Richard,

 

I've gone from 15" to 13" on my VVC and the improvements has been phenomenal - the cycle wings & stays don't need changing but IMHO the smaller wings look better with the smaller tyres.

 

Nick