bgood

iTrader: (2)

I'm gonna be needing some new tyres soon for my 93 WRX and I would like to get some Vredestein Ultracs.

Currently I have 215/40 17 Toyo T1S tyres but the Ultracs aren't available in this size, for a 17" they are only available in the following sizes;

205/45 ZR 17 88 W XL
215/45 ZR 17 87 W
225/45 ZR 17 94 W XL
235/45 ZR 17 94 W
245/45 ZR 17 95 W

According to the SIDC FAQ the original tyre/wheel size was 205/55 VR 15 so I've used an online tyre size calculator to compare and 205/45 ZR 17 seems to be the closest match - rolling radius of 190.54cm for the original as opposed to 193.62cm for the Ultrac so my speedo will only read 1.6% higher than it should, i.e. when the speedo says i'm doing 30 I'll actually be doing 30.5, so that seems reasonable.

But the question is am I gonna notice a difference going from 215 width to 205 width (I presume not) and can anyone confirm I've got all this right/is there anything else I need to be aware of before I spend my hard earned on a set of Ultracs please???

bgood

iTrader: (2)

Anybody?

Carl Davey

iTrader: (3)

I actually went 215/45 working on the theory the speedo reads approximately 10% low when the car leaves the factory. No issues on standard suspension. Prodrive fitted 205/45's to the RB5 however.

bgood

iTrader: (2)

Cheers for the reply

Interesting info about the RB5, you'd like to think Prodrive know what they were doing so that's promising

bgood

iTrader: (2)

OK, after a bit more research I'm thinking now that 215/45/17 is in fact the better option.

As standard the speed over reads, i.e. says 60 but actual speed 58.5 for example.

Fitting the 215/45/17's has the opposite effect so IF your speed was deadly accurate and it said 60 you would in fact be doing 61.5 for example.

So by fitting the 215/45/17's I'll actually be making my speedo more accurate

Oh and they're cheaper in that size too

Carl Davey

iTrader: (3)

That was my thinking with regards to the speedo. Pricewise there wasn't a huge difference for GSD3 F1's although IIRC they don't come in 205/45 (the other option is 215/40). I think i paid something like £350 for four fitted. It's a shame the R888's or A048's aren't quite so cheap.