Discussion
i know we measure ride heights from the chassis, but after fitting 17 tyres, those measurements will be incorrect if the radius has changed (which it has on mine as i run 235/40/17.
Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
SSPPGG said:
i know we measure ride heights from the chassis, but after fitting 17 tyres, those measurements will be incorrect if the radius has changed (which it has on mine as i run 235/40/17.
Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
The wishbones need to be level ,I can`t see different size wheels making a difference ,the overall diameter should be within a few mm if you spec the tyres .Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
I would have a look on a tyre calculator.
I measure from the front and rear corner plates (jacking points) on a flat level floor, you need around 15mm diference front to rear
SSPPGG said:
i know we measure ride heights from the chassis, but after fitting 17 tyres, those measurements will be incorrect if the radius has changed (which it has on mine as i run 235/40/17.
Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
Why are you going for 235/40/17 ? 245/40/17 are better suited.Is there another reference point that works, such as starting by getting the front and rear upper wishbones horizontal, and setting all the suspension from there.......??
Original diameter 631mm
245/40/17 628mm
235/40/17 620mm that must throw your speedo out and rev higher when cruising.
Edited by SILICONEKID340HP on Wednesday 9th January 21:03
I went to 205/40 17s last summer. Would have preferred 215/40 17s but did not find them.
You can do the maths yourself. The width is in millimetres, the sidewall height is a percentage of the width.
The 40 is an aspect ratio, so the side wall height of your tyres is 235mm x40%, ie 94 mm.
Your wheel diameter is 17 inches, which is 17 x 25.4 mm, or 431.8mm. So total diameter of your wheel and tyre is 431.8 + (2 x 94) = 619.8 mm.
The standard rears are 16 inch wheels. What tyres? Mine are 225/50, so the side wall is 225x50%, ie 112.5mm
Wheel and tyre therefore 112.5 x 2 plus 16 x 25.4 = 225 + 406.4 = 631.4mm
So in theory your tyres are slightly too small for the rears. About half an inch.
The standard fronts on my car are 15 inch wheels and the tyres are 205/55. 205 x55% x2 = 225.5 mm. 15x25.4 = 381. 225.5 + 381 = 606.5.
So your choice of tyres on 17 inch wheels are in between the standard front and rear tyres........assuming mine are standard.
But at least you can now see the calculation method. And it suggests you need to lower the front slightly and raise the rear, both by half an inch.
And yes, I am an accountant, and yes, I do sleep in my anorak
You can do the maths yourself. The width is in millimetres, the sidewall height is a percentage of the width.
The 40 is an aspect ratio, so the side wall height of your tyres is 235mm x40%, ie 94 mm.
Your wheel diameter is 17 inches, which is 17 x 25.4 mm, or 431.8mm. So total diameter of your wheel and tyre is 431.8 + (2 x 94) = 619.8 mm.
The standard rears are 16 inch wheels. What tyres? Mine are 225/50, so the side wall is 225x50%, ie 112.5mm
Wheel and tyre therefore 112.5 x 2 plus 16 x 25.4 = 225 + 406.4 = 631.4mm
So in theory your tyres are slightly too small for the rears. About half an inch.
The standard fronts on my car are 15 inch wheels and the tyres are 205/55. 205 x55% x2 = 225.5 mm. 15x25.4 = 381. 225.5 + 381 = 606.5.
So your choice of tyres on 17 inch wheels are in between the standard front and rear tyres........assuming mine are standard.
But at least you can now see the calculation method. And it suggests you need to lower the front slightly and raise the rear, both by half an inch.
And yes, I am an accountant, and yes, I do sleep in my anorak
Edited by Quietlybonkers on Wednesday 9th January 21:40
LuckyLucky said:
I skimmed that Anthony 
.
Daz, I will be running;
Front,...235/40/17
Rear,....255/40/17
Proper R1R rubber that is actually that wide as they have square shoulders unlike road tyres that always have less width then the tyre size suggests!
It's made me think. I will keep the same tyres, but raise the rear ride height to improve the handling. .Daz, I will be running;
Front,...235/40/17
Rear,....255/40/17
Proper R1R rubber that is actually that wide as they have square shoulders unlike road tyres that always have less width then the tyre size suggests!
LuckyLucky said:
I skimmed that Anthony .
Daz, I will be running;
Front,...235/40/17
Rear,....255/40/17
Proper R1R rubber that is actually that wide as they have square shoulders unlike road tyres that always have less width then the tyre size suggests!
I take it you have power steering with those wide fronts then Peter. ?.Daz, I will be running;
Front,...235/40/17
Rear,....255/40/17
Proper R1R rubber that is actually that wide as they have square shoulders unlike road tyres that always have less width then the tyre size suggests!
LuckyLucky said:
Yep, a lovely Subaru P/S rack fitted!
Just sold my scooby, have you listed the conversion on here previously ?.....if not got any details as most conversions involve the corsa electric motor and having had issues previously on the wife's meriva I wouldn't touch one of those with a chim drivers ....Quietlybonkers said:
I went to 205/40 17s last summer. Would have preferred 215/40 17s but did not find them.
You can do the maths yourself. The width is in millimetres, the sidewall height is a percentage of the width.
The 40 is an aspect ratio, so the side wall height of your tyres is 235mm x40%, ie 94 mm.
Your wheel diameter is 17 inches, which is 17 x 25.4 mm, or 431.8mm. So total diameter of your wheel and tyre is 431.8 + (2 x 94) = 619.8 mm.
The standard rears are 16 inch wheels. What tyres? Mine are 225/50, so the side wall is 225x50%, ie 112.5mm
Wheel and tyre therefore 112.5 x 2 plus 16 x 25.4 = 225 + 406.4 = 631.4mm
So in theory your tyres are slightly too small for the rears. About half an inch.
The standard fronts on my car are 15 inch wheels and the tyres are 205/55. 205 x55% x2 = 225.5 mm. 15x25.4 = 381. 225.5 + 381 = 606.5.
So your choice of tyres on 17 inch wheels are in between the standard front and rear tyres........assuming mine are standard.
But at least you can now see the calculation method. And it suggests you need to lower the front slightly and raise the rear, both by half an inch.
And yes, I am an accountant, and yes, I do sleep in my anorak
Why make it difficult? just use a tyre calculator.
http://www.kouki.co.uk/utilities/visual-tyre-size-...
You can do the maths yourself. The width is in millimetres, the sidewall height is a percentage of the width.
The 40 is an aspect ratio, so the side wall height of your tyres is 235mm x40%, ie 94 mm.
Your wheel diameter is 17 inches, which is 17 x 25.4 mm, or 431.8mm. So total diameter of your wheel and tyre is 431.8 + (2 x 94) = 619.8 mm.
The standard rears are 16 inch wheels. What tyres? Mine are 225/50, so the side wall is 225x50%, ie 112.5mm
Wheel and tyre therefore 112.5 x 2 plus 16 x 25.4 = 225 + 406.4 = 631.4mm
So in theory your tyres are slightly too small for the rears. About half an inch.
The standard fronts on my car are 15 inch wheels and the tyres are 205/55. 205 x55% x2 = 225.5 mm. 15x25.4 = 381. 225.5 + 381 = 606.5.
So your choice of tyres on 17 inch wheels are in between the standard front and rear tyres........assuming mine are standard.
But at least you can now see the calculation method. And it suggests you need to lower the front slightly and raise the rear, both by half an inch.
And yes, I am an accountant, and yes, I do sleep in my anorak
Why make it difficult? just use a tyre calculator.
http://www.kouki.co.uk/utilities/visual-tyre-size-...
Edited by Quietlybonkers on Wednesday 9th January 21:40
LuckyLucky said:
Yep, a lovely Subaru P/S rack fitted!
How is the steering now ? does it feel much different ! did ou do the coversion or have it built ..I can`t believe those tyres don`t catch ..I had problems with the rear outriggers catching one side but not the other. what have you done with the front end to fit the 235`s
Edited by SILICONEKID340HP on Wednesday 9th January 22:59
SILICONEKID340HP said:
LuckyLucky said:
Yep, a lovely Subaru P/S rack fitted!
How is the steering now ? does it feel much different ! did ou do the coversion or have it built ..I can`t believe those tyres don`t catch ..I had problems with the rear outriggers catching one side but not the other. what have you done with the front end to fit the 235`s
Edited by SILICONEKID340HP on Wednesday 9th January 22:59
As for the front tyres Daz, haven't fitted them yet but if the saw needs to come out then so be it!
Actually Retrowheels has the same wheels and tyre setup
.Quietlybonkers said:
And yes, I am an accountant, and yes, I do sleep in my anorak
Been a flurry of accountant jokes on the "Jokes" thread on my employers forums...What do accountants use for contraception?
Their personality!
What is the collective noun for a group of accountants?
A Bidet.
Everyone knows what one was is but not what they are for.
Actuaries are people who found accountancy to be too exciting.
rigga said:
I take it you have power steering with those wide fronts then Peter. ?
thanks all, i know its only a few mm difference, but i just wondered how other folk did it.I'm using the same R1R sizes as peter, 235 fronts, 255 rears, both 40/17, which is as close as you can get to spec with the R1R.
with the ride height set at the moment about 15mm high (till the drive is finished and the huge "step" i have to overcome to get into the garage is gone), on the griff at least, I've had nil clearance issues, other than the back of the lamp pod, which protrudes into the inner arch at the front a little (maybe 'cos i've a 7 inch lamp upgrade fitted), but this is only on full lock.
Daz, good point re the tyre calculator. I just like to understand the principle involved, so that when I don't have a tyre calculator to hand and am buying tyres, and cannot find exactly what I want, I can work out the alternatives. I suppose it helps that I can do the maths in my head.
SILICONEKID340HP said:
Why are you going for 235/40/17 ? 245/40/17 are better suited.
Original diameter 631mm
245/40/17 628mm
235/40/17 620mm that must throw your speedo out and rev higher when cruising.
sorry, thats my fronts, rears are 255. with the LS fitted, i can use the electronics to adjust the speedo output, but the 10mm difference you note would account for only 1.6% speedo or rev change, so 2500 revs would become 2540 revs. or indicated 80 would become actual78Original diameter 631mm
245/40/17 628mm
235/40/17 620mm that must throw your speedo out and rev higher when cruising.
Edited by SILICONEKID340HP on Wednesday 9th January 21:03
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