SP12's and Tires sizes
Discussion
Just received my shiney new Silver SP12's all safe and sound after their 16000KM journey (Thanks Tim).
The quoted tire sizes are Front 215-40-17.
Rear 225-40-18 or 245-35-18.
The problem here (in Australia) 215-45-17 are what's available.
I.e. 45 side wall instead of 40.
To keep the slightly nose down stance/balance, will I need to increase the rears by the same amount i.e. from 225-40 to 225-45 or 245-35 to 245-40?
If I do, will they fit with out rubbing?
I think I can live with the speedo being off a bit.
If I order the tires in the next few hours, they'll be fitted tomorrow.
I've done a search, but in my anxious state haven't found the answer.
Cheers.
The quoted tire sizes are Front 215-40-17.
Rear 225-40-18 or 245-35-18.
The problem here (in Australia) 215-45-17 are what's available.
I.e. 45 side wall instead of 40.
To keep the slightly nose down stance/balance, will I need to increase the rears by the same amount i.e. from 225-40 to 225-45 or 245-35 to 245-40?
If I do, will they fit with out rubbing?
I think I can live with the speedo being off a bit.
If I order the tires in the next few hours, they'll be fitted tomorrow.
I've done a search, but in my anxious state haven't found the answer.
Cheers.
Edited by OZRob on Wednesday 22 October 12:17
I run Toyo R888s on my SP12s, and the sizes are 215/45 17 and 235/40 18, which gives the nose down stance.
I did find at first that, being 888s, which are rather wide shouldered and about two sizes larger than other tyres in those sizes, I had some issues with the tyre catching on the rear left wheel arch on track days - easily solved by raising the ride height a tad
I did find at first that, being 888s, which are rather wide shouldered and about two sizes larger than other tyres in those sizes, I had some issues with the tyre catching on the rear left wheel arch on track days - easily solved by raising the ride height a tad
PS, the standard 15/16 tyre sizes are 205/55 15 and 225/50/16. Wheel & tyre diameters are 606mm and 631mm respectively, 25mm difference
The recommended sizes you came up with 215/40 17 and 225/40 18 give 603mm and 637mm respectively, so a 34mm difference
The sizes I have used are 215/45 17 and 235/40 18 (as the rear wheels are 8J) and these give 624mm and 645mm respectively, slightly larger front and rear, but a 21mm difference
All would suit - the difference in every case is not more than the difference between a new tyre and a fully worn one (13.2mm). I calculate that with my tyre sizes the speedo will be out by 1.54 mph at 70 mph....not worth worrying about.
The recommended sizes you came up with 215/40 17 and 225/40 18 give 603mm and 637mm respectively, so a 34mm difference
The sizes I have used are 215/45 17 and 235/40 18 (as the rear wheels are 8J) and these give 624mm and 645mm respectively, slightly larger front and rear, but a 21mm difference
All would suit - the difference in every case is not more than the difference between a new tyre and a fully worn one (13.2mm). I calculate that with my tyre sizes the speedo will be out by 1.54 mph at 70 mph....not worth worrying about.
ianwayne said:
I am surprised that those clear your arches. I have 225/50 x 15 on the front of mine (same diameter as 205/55) and the tyre is only a few mm away from the arch on half-lock. Do you have the same offset as standard?
They clear easily, but as you can see I have my ride height set a tad higher. Also, 888s on my car come with 5mm of tread new, and generally have about 3-4mm or tread when in use, so there's 8mm (2 x 4mm)of the diameter difference straight away compared with brand new 225/50 15s. IMHO its the tyre width that makes the most difference on fronts, and i have never gone bigger than 215s.....Gassing Station | Chimaera | Top of Page | What's New | My Stuff