Wheels/tyres downsizing from 16" to 13"/14"

[glasgow]

Hello, all.

 

I would like to change my 16" tyres to either 13 or 14". Car is Roadsport, SV, 1.8 K series, 140bhp, used mainly for road/touring/blatting. I have Avon ZZ3 on 16x45x205 front & rear. I would like to change to more grippy tyres.

 

I understand I may need to do some changes to the suspension setup and speedo but tyres HAVE to be :

 

A- Grippy on damp roads

B- No changes required to the wing stay (ie tyre rolling circumference less than 180cm, 5' 10.87" which is equivalent to size 13x70x185 )

 

I have been watching a couple of current threads and had a good look at the archive and here is my understanding of the current available legal road tyres:

 

- Avon ZZS: may be good in wet but doesn't come in the right size (the closest is 13x55x155 which may be too small)

- Avon CR28: comes in 13x60x205 and 14x60x185

- Toyo R888R comes in 13x60x205 and 13x60x185 and 14x60x185 but wet grip E

- Uniroyal Rainexpert3: good price and comes in 13x70x185 (but speed rating 118mph and also it is designed for "normal" cars so not sure about performance in light weight cars)

- Uniroyal Rainexpert: comes in 14x60x185 speed rating 130mph.

 

I am having difficulty deciding which one to go for and appreciate your views please

 

Regards

 

Ahmed

 

 

 

 

 

[Mucus72]

I'm not an expert, there will be some along soon regarding rolling radius Ahmed. I would say that there are more 13" options than 14" for tyres full stop. I happily ran Yoko A021s on 13" and 14" before they ceased to be available, and they were good in damp conditions.

I would consider changing your wingstays because there will be a massive gap if you are not careful. That then means that you need to worry less about trying to fill the gap out with a challenging very high sidewall ratio tyre option.

You can easily adjust speedo to suit the new rolling radius. I think 13" with a nice big sidewall are lovely and comfortable for all types of sevening.

I don't have enough experience of any of the options you mentioned regarding best grip in the wet. My options on my next car will be ZZS for road and damp or cold circuit, and ZZR for sticky dry hot circuit.

In my old car I used A021R for the former and 888 for the latter. But with a heavy right foot, there is no such thing as wet grip in a Seven ;)

[glasgow]

Thank you Mucus. I am really not keen at at changing the wing stay. If I leave a big gap, is it just the "look" or more "lifting power on the wing?

I think my options should be narrowed to:

13x60x205 (CR28 or R888R) or  13x60x185 R888R

Also for the wheels, any suggestion for light weight not expensive ones please.

 

Thank you

[Mavic82]

If you must downgrade :-) why not consider 15" wheels, with the right tyre size there is no need to change wings or wing stays.

[glasgow]

My thinking is if I am going for tyre change, I just do it once and for all. People with 15" change to 13" so it may be wise just to go to 13" in one step. 

Size 205x60x13 will only reduce the height gain with 6mm therefore my current wing stay should be ok. (185x60x13 will reduce the ride by 19mm)

[Wrightpayne]

Ahmed,

IIRC yours is a SV - I think with 13's all around you'd need 8" rears with 205/60 13 tyres to look right and unless you're sprinting the norm on the front would be 6" rims with 185/60 tyres. With this combo you will probably need to play around with the ride height at the front to get clearance under the sump and it can also affect the handling (cornering). I dont think 185/60's on 6" rims would look right on the rear of an SV

As Mavic suggested I'd look at the 15's because there is a reasonable amount of tyre choice (Toyo and Kuhmo to name a couple) and it also means minimal changes elsewhere on the car.

Caterham have some silver 15" wheels in their clearance section of the online store - £100.80 each though you'd need to check with them that they are suitable. Edited to say 15's are usually 10 spoke - ones in the clearance section have 12 hence why I suggest checking - may be CSR fronts?

Just my 0.02p worth.

Ian

[Mucus72]

Ian, 6" rims front and rear are standard on SV. My old SV had this width wheel front and back on a mixture of 13 and 14" wheels. In my opinion, no need to go wider up to around 150bhp. Didn't look bad, and gave progressive front to rear balance on track. It was ideal.