13 Or 15 Wheels

[KenO]

I am looking for some advice on wheel and tyre size for my 2B with sliding pillar front suspension, rear arches are wider than normal with 100mm from the rear axle to outside of rear wheel arch, front mudguard width is 200mm. I was thinking 7 x 13 Minilites or 7 x 15 Minilites with 205/50 x ? Tyres. Any advice would be appreciated.

Ken

[Guest mower man]

Either should work the bigger side wall of 13 inch tyres are suposed to be more comfy compared with 15 's wich are better for slightly fiercer fast road or track day use I used 15 inch 6.5 with 205 /50 's for12 years felt fine to me mick

Edited June 29, 2015 by mower man

[kevin the chicken]

I can't advise you on the actual size wheels you need but look at the availability and prices of the type of tyres you are likely to fit before plumping for a particular size. I wanted to fit a dry weather biased tyre as I have no wet weather gear and found that it was actually cheaper to buy some new wheels to be able to get the tyres I wanted. I was very limited in choice until I changed to 15 inch wheels and then suddenly the world was my oyster!

[Guest 2b cruising]

Hi. 15" are the common size, helping to fill the massive rear arches.

Ideal size for weight is 195 x 60.

205 will do ok but watch it in the wet.

Mine are on an et of 15 which is as supplied by RH.

Lots of people use et 25 or even 35 on deeper dish wheels.

There are of coarse lots of permutations and the choice is yours.

I have only pointed out the most common and given the reasons.

Forgot to mention J 6.5 or J 7 . Either width tyre I have mentioned. The actual optimum for 6.5 would be 195. Optimum for 7 would be 215. These are optimum sizes but in your case as you are not rallying either rim for eithe tyre would do.

I studied this in quite depth when thinking about altering mine. That why when I needed new tyres I went down a width to 195.

No need for you to tell me, I will be off now and I will close the door on my way out.

Edited June 29, 2015 by 2b cruising

[agent_zed]

You will need at least 14's. The sliding pillar works differently to most suspension setups. The hub moves up a rod between 2 fixed arms the lower arm is within the wheel well. If the wheel is too small the bottom nut on the hub will hit the inside of the wheel rim.

 

I would go for 15's to be safe.

[kevin the chicken]

Zed is right, go for 15s, 14s gives you very little choice of tyre.

 

[KenO]

Thanks to all who replied to my post, I am almost there with the tyre and wheel size, would the V speed rating on the lower profile tyres affect the IVA test.

[Bob Tucker]

At IVA you need to fill in maximum speed capability of the car (IIRC)....just make sure the tyre is rated higher.

Bear in mind the awful aerodynamics of the car will limit its top speed

[rthomas69]

I went for 15's based on availability of tyres...oh & the fact that I got some focus alloys for £11 on evilbay

[Guest 2b cruising]

Bob is right.

You can get a tyre that is not rated enough, but you cannot get a tyre that is over the top.

The higher the rating, the stronger the tyre.

[maccavvy]

ive got 15s on my SP 2b. and even then ive bottomed it out and damaged a wheel.. 13s would be screwed by now.

 

its a good balance between ride and handling.. ive got yoko parade 2s on.. never had an issues although some report poor wet handling.

 

I don't use it in the wet but you have to be careful anyways imo.

 

mine are compomotive wheels that look like minilites.

Edited June 29, 2015 by maccavvy

[agent_zed]

for top speed it is possible to work out a theoretical absolute top speed with a few calculations. If we ignore wind resistance the top speed is governed by how fast the engine can go (max rpm) and the gearing. So if you know your max continuous RPM the gear ratio of 5th, the gear ratio of the diff and the circumference of the tyre that will be the very fastest you will be able to go and it wouldn't matter if your engine was more powerful or not as it cannot rotate any faster. It would be hard for a tester to argue.

 

If you put on a tyre with a bigger rolling diameter then in theory you have increased the gearing and the theoretical top speed is increased. But it would require more power to get there.

 

Obviously in the real world the actual top speed would be lower as engine power also plays a part to push through the air and clutch slip is also possible, and you might not have enough road depending on acceleration rates.

 

after saying all that i think i just used the sierra's top speed from the haynes manual