tyre noob question

[RichieSounds 0]

i'm not sure quite what tyres to go for - i've got the opportunity to buy a set of bbs rx 16" rims with no tyres. I'm coming from owning standard 15" speedlines so am accustomed to the flexible ride of these 205/50/15 tyres, and like it. so if i go for the 16" rims can i stick 50 profile tyres on them, or am i limited to specific tyre sizes? If i take the 205/40/16 tyres i'm presumably losing some depth of tyre, but gaining radius of rim, so ending up with less 'squish'. is that correct? Could i even put 55 profile tyres on these rims, hence increasing the rolling circumference?

[dukest 0]

you don't really want to alter your overall wheel+tyre diameter as it will screw up your speedo etc.. better off with the 205/40/16 tyres and decent suspension to make up for lack of squish..

[RichieSounds 0]

so the end effect of putting say 55 depth tyres on a 16" wheel would end up with a longer circumference, and a greater overall radius.

 

15" = 38.1 cm

16" = 40.64 cm

17" = 43.18 cm

 

205/50/15 depth: 50% of 205 mm = 10.25 cm

205/40/16 depth: 40% of 205 mm = 8.2 cm

205/45/16 depth: 45% of 205 mm = 9.225 cm

205/50/16 depth: 50% of 205 mm = 10.25 cm

215/40/16 depth: 40% of 215 mm = 8.6 cm

215/50/16 depth: 50% of 215 mm = 10.75 cm

 

So.

 

15" rim with 205/50/15 diameter: 38.1 + (10.25 x 2) = 58.6 cm

 

16" rim with 205/40/16 diameter: 40.64 + (8.2 x 2) = 57.04 cm

16" rim with 205/45/16 diameter: 40.64 + (9.225 x 2) = 59.09 cm

16" rim with 205/50/16 diameter: 40.64 + (10.25 x 2) = 61.14 cm

16" rim with 215/40/16 diameter: 40.64 + (8.6 x 2) = 57.84 cm

16" rim with 215/50/16 diameter: 40.64 + (10.75 x 2) = 62.14 cm

 

17" rim with 215/40/17 diameter: 43.18 + (8.6 x 2) = 60.38 cm

 

So you hear of people saying that the handling of their Corrado changes (ie 'tram lining' at speed) once they've stuck on 17" rims. Not surprising. But the end effect of enlarging your rims conservatively and putting 16" rims could have the same effect if you put on 50 depth tyres. But you may just get away with it on 16s with 40 depth tyres...

 

I bought my wheels, and think they don't quite fill the arches enough, but that's probably a case of needing to lower the suspension a little as opposed to putting on larger profile tyres.

 

I've got a feeling i've just re-invented the 'tyre size calculator' I've heard about but not seen. Can someone link me to it please?

[dr_mat 0]

Without recalling where the tyre size calculator lives, istr that most people go with either 205/50/15, 205/45/16 or 205/40/17 for VR6 Corrados.

[RichieSounds 0]

i've just put 215/40/16s on mine. I've got Koni TAs and Eibach springs. It's pretty firm, and harrowing when you encounter a pot hole unexpectedly, but feels tight around roundabouts. the tyres are pirelli p zeros. Anyone else running a setup similar to this?

[Yandards 0]

Without recalling where the tyre size calculator lives, istr that most people go with either 205/50/15, 205/45/16 or 205/40/17 for VR6 Corrados.

 

In the wiki here

[BILLCOR 1]

i've just put 215/40/16s on mine. I've got Koni TAs and Eibach springs. It's pretty firm, and harrowing when you encounter a pot hole unexpectedly, but feels tight around roundabouts. the tyres are pirelli p zeros. Anyone else running a setup similar to this?

 

As above, 205/45/16 is the ideal tyre for 16's

[RichieSounds 0]

interesting - how come i wonder? 205/40/16 comes closer to the radius of the standard wheels... am i missing something or is my maths wrong.

 

thanks for link to the wiki, that page is really useful.

[__Andy__ 0]

i currently have 205/40/17's, bought new wheels so will be running 205/45/16. also have koni and eibach suspension so similar to your setup, lowered 40mm and like you said its quite hard. cant wait to see what the cars like with the 16's on tho...

[dinkus 10]

interesting - how come i wonder? 205/40/16 comes closer to the radius of the standard wheels... am i missing something or is my maths wrong.

 

thanks for link to the wiki, that page is really useful.

 

205/45/16 is the closest match to the standard VR Speedlines which ran 205/50/15 tyres, because your maths is a little wrong.

 

You need to compare like with like. Your maths was using the full diameter of the wheel, but only the sidewall of the tyre once.

 

If you look at the tyre and wheel as a whole, you need to include the tyre sidewall twice (once at the top of the wheel and again at the bottom). When you do that, the maths work out that the 205/45/16 is 0.84% bigger than the 205/50/15 and the 205/40/16 is 2.66% smaller.

 

The calculator on the tyre bible site (linked from the wiki article) will help you out :)

[RichieSounds 0]

great stuff dinkus. i was being a doofus. that makes a whole lot of sense.

 

so the tyres i've just put on my car are actually smaller than the originals. oh well. i think i can live with that!! i wish i'd seen that calculator before buying my nice new tyres though. It would have influenced that decision.

 

veedub21 how come your downsizing? tram lining or is the ride too hard?

 

cheers guys.

[__Andy__ 0]

going to 16's as i found a set of porsche design 90's cheap. also am not too keen on my 17's am trying to sell them at the mo but not too bothered if they dont sell as i will keep them, gives me options then. currently lowered 40mm and with the 17s on it looks like its on stilts! so eventually will lower it 60mm on the 16's, will be coilovers once ive got the money...

[junkie 0]

The tram lining is when its wider tyres/wheels not the overall diameter, as it digs into the grooves in the road more then follows it, could be seen as going 17's to some as generally people go wider at the same time.