Tyres and sidewall heights

[ClassicChimaera]

I'm just looking at Uni royal Rainsport 3 tyres.

My preferred choice is
Front 215 45 17 a change in sidevwall from 215 40 17
Hopefully it won't rub.

Also considering going up on the rears from 245 40 17 to 245 45 17

Can anyone work out the difference in outside dia/ circumference please.

I tend to run my ride height at least as high as standard so have what looks like plenty of room in the wheel arches.

Thanks Al.

Edited by ClassicChimaera on Friday 30th December 19:17

[SILICONEKID345HP]

Seen a few Chimaeras with 245/45/17 ,they seem to be alot more expensive .

Think you are going to have problems with the fronts .

Edited by SILICONEKID345HP on Thursday 29th December 21:24

[J400GED]

ClassicChimaera said:

I'm just looking at Uni royal Rainsport 3 tyres.

My preferred choice is
Front 215 50 17 a change in sidevwall from 215 40 17
Hopefully it won't rub.

Also considering going up on the rears from 245 40 17 to 245 45 17

Can anyone work out the difference in outside dia/ circumference please.

I tend to run my ride height at least as high as standard so have what looks like plenty of room in the wheel arches.

Thanks Al.

You're tyre wall - and therefore your radius - will be 5% of 245 taller - 12.25mm greater radius 76.97mm greater circumference.

[QBee]

215/50 17 is a diameter of 215+431 =646mm front
245/45 17 is a diameter of 220 +431 = 651mm rear.

I woul suspect both, and particularly the fronts, will be too big. You might get away with 245/45 17 at the rear - i have got away 235/45 17, which is only 9mm smaller.

But the fronts should be 215/45 17. (=625mm)

[ClassicChimaera]

Hmmm. I think I better go for 45's on the front.
The reas sound a bit touch and go too.

Daz what size are you using, yes the bigger tyre and heights are more expensive and have a higher Y rating which might make them harder!!!

I'll have yours please sir

[SILICONEKID345HP]

235 45 17 Rear and they look spot on .

Fronts are 16 "

[ClassicChimaera]

SILICONEKID345HP said:

235 45 17 Rear and they look spot on .

Fronts are 16 "

Yes they do.

So tell me what the fronts 16's are as you have a very good balance in wall height front to back.

I have 7.5 j wheels allround.

If you get a mo can you take a pic of the rears so I can see the arch Daz please. No worries either way but I'm ready to pull the trigger,,,,,

I dunno how Anthony does it but the ones he posted the other day (I can't remember what thread it was on! ) are like twenty quid cheaper.

I was on Camskill site.

There's a chart I used before but I'll be buggered if I can find where I've saved it!


B

[737 FLF]

Here you go....

http://www.kouki.co.uk/utilities/visual-tyre-size-...

[QBee]

The people I use are Click on tyres up in God's own county.

http://www.clickontyres.co.uk/

I have bought several sets of tyres from them, good service. When I ordered 94Y for my Saab, I realised after they arrived that I should have ordered 97Y XL. Rang them, they organised a fresh delivery and collection all in one, and swapped the tyres out the next day, all for the difference in price. Top service.

In your price comparison with the high street, don't forget that you will have to pay to have them fitted and balanced. Probable cost £10-15 per tyre.

[bobfather]

This is a great tool for seeing the dimensional changes as tyre sizes change

http://www.rimsntires.com/specspro.jsp

[Richard 858]

You could also try www.willtheyfit.com

[hillclimbmanic]

I've fitted 215/45x17 front, on 7.5"
245/40x17 rears, on 8.5"

The closest Rolling circumference available, to standard

[ClassicChimaera]

Richard 858 said:

You could also try www.willtheyfit.com

Bingo ,,, yes this is the one I settled on Richard, been on it hours and my minds awash with numbers.

By eck is this a game

Important numbers to remember that's assuming original Tvr sizes were using 7.5 inch wheels both front to rear.
Front 205/55/15. 606.5 mm outside diameter
Rear 225/50/16 631.4 mm outside diameter

My tyres are near as damn it spot on, slightly smaller at
F 215/40/17 603 mm
R 245/40/17 627 mm

I have no rubbing issues.

I'd like to do what Daz has done by going to the 235/45/17 rears but that takes the outside Dia from 631.4 to 643.3 mm, that's ok a bit higher geared but if I stay with 215/40/17 fronts there going to look to small, car will look like a drag car with big rear tyres, but the only other tyre for the fronts then becomes a 215/45/17 but the problem with that is it takes the outside Dia on the fronts up from
606 mm to 625 mm give or take a fraction.
Rubbing issues on full lock are likely as could fouling on the wishbones!

Hmmm.
I want frigging 16 inch front wheels now!!!!!

I've considered 225/40/17 on the fronts but the width might cause tracking problems although the outside Dia is close to original spec, 606.5 to 611.8 mm

For awhile now if felt the cars a bit under geared so getting the biggest tyre in there would help.

I might risk the whole hog and go for F 215/45/17 R 245/45/17 which is 20.5 mm bigger fronts and 20.9 mm bigger rears than standard.
So basically the tyre sits 10 mm further out either side of the tyre from standard settings. Obviously these tyres are wider too.

It's a tight fit.
I think I need it on the ramp to check things closer. I'll do some checks before committing, I can see me wasting a few hours to find I'll just buy the size I'm already using, I've wasted about 10 hours trying to work it out already

ETA this is using a 7.5 inch wheel allround so those who are using 8 inch rears will calc it differently.
I'm using 7.5 allround I'm considering using 5 to 10 mm spacers if I have to.

Edited by ClassicChimaera on Friday 30th December 15:42

[ClassicChimaera]

hillclimbmanic said:

I've fitted 215/45x17 front, on 7.5"
245/40x17 rears, on 8.5"

The closest Rolling circumference available, to standard

And you have no rubbing issues with that front size.
Cool

[ClassicChimaera]

I'm taking a chance, life's full of those babies, might be great or it might not work but I've decided to order
215/45/17 fronts
235/45/17 rears

Can't see a problem with the rears but might get some rubbing on the fronts.
I've considered widening the track slightly for awhile now so if I have to use spacers upto 10 mm I will do.
Better order some longer wheel studs if that's the case.

I drove Riches car that had wheel spacers fitted and it tracked very good.

[QBee]

You won't have an issue with either of those.
I have run those sizes on my car with no issues.
I have had several sets of the fronts - never a problem.
If you are very unlucky and get a little rubbing on the rear outer wheel arch (and I don't expect you will), the solution is a small ride height increase.

[ClassicChimaera]

QBee said:

You won't have an issue with either of those.
I have run those sizes on my car with no issues.
I have had several sets of the fronts - never a problem.
If you are very unlucky and get a little rubbing on the rear outer wheel arch (and I don't expect you will), the solution is a small ride height increase.

I run my ride height about 5 mm higher than standard and still I've caught the front valance on high curbs etc scratching the feck out of the paint so for road going purposes I'm thinking this is ok.
Cheers for your help Anthony, and others I might add

Only by looking closer at these sizes did I realise on 17 inch wheels my tyres are actually rotating faster than the standard set up (slightly smaller) I wondered why my brakes are so good and it felt lower geared, I'm sure I subconsciously knew

I'd liked to have gone to the 245/45/17 because you'd have a serious gearing uplift and I like the sound of that but I've bottled it

Standard rear Dia 631 mm as opposed to the 245/45/17 being 652 mm so quite an increase.
I have huge torque 345/350 ft lb ( well I think it is ) so think the car would benefit from this higher gearing.

Look at the difference in circumference and you'll see it seems a large change.

Hopefully the fronts which I'm most worried about will fit ok, if they do the business and the rears still can take a larger tyre I'll go for the 245 someday but maybe this is the best balance.
Without delving deeper into the already scary inteweb thing
Y rating I understand the top speed but the 94 or 99 after it,
Does the higher number suggest a harder tyre, a higher load rating, if so then the 245 could be more likely to break away as it has a 99 rating, I'm assuming the 99 would be a firmer tyre wall rather than some compound change?

Edited by ClassicChimaera on Friday 30th December 18:42

Edited by ClassicChimaera on Friday 30th December 18:48

[QBee]

http://www.blackcircles.com/general/load-rating

The 94 or 99 are load ratings - they correspond to a number of kilos the tyre can carry. Higher the number, the greater the load it can carry. My 4x4 tyres are rated 106 or 108, but it's over 2 tonnes of car.

Sort of follows that the higher the rating, the stiffer the sidewall. My Federal 595 RSRs were 83 and 87 rated, and my Toyo R888s were 91 or 92 - it was noticeable that with the dampers on a track hard setting, the Federals were ok on the road and absorbed the bumps, whereas the stiffer Toyos shook my fillings out until I softened the dampers.

I wouldn't go higher than 94 for a Chimaera

[ClassicChimaera]

QBee said:

http://www.blackcircles.com/general/load-rating

The 94 or 99 are load ratings - they correspond to a number of kilos the tyre can carry. Higher the number, the greater the load it can carry. My 4x4 tyres are rated 106 or 108, but it's over 2 tonnes of car.

Sort of follows that the higher the rating, the stiffer the sidewall. My Federal 595 RSRs were 83 and 87 rated, and my Toyo R888s were 91 or 92 - it was noticeable that with the dampers on a track hard setting, the Federals were ok on the road and absorbed the bumps, whereas the stiffer Toyos shook my fillings out until I softened the dampers.

I wouldn't go higher than 94 for a Chimaera

Very amusing and I totally agree which is why I've ordered the lower rated tyres.

This all started again the other day when I changed my damper settings, car felt good, but I'd also dropped my tyre pressures to 20 psi all round.
I'm thinking for local driving I'll have softish tyre pressures etc so helping compliance.
By hopefully getting these tyres about right I can then determine what to do ( if anything) with shocks.

Ive been driving a number of far more modern vehicles recently, puts the TVR into perspective a bit, it's not as bad as I sometimes whine on about.

I've changed my Protech twin shocks damper settings two clicks less allround on the rebound knob
So
8 bump
6 rebound
This is from a maximum of 12 clicks from hard.
For winter driving and with the 20psi tyre pressures it's feeling very predictable and still turns in well considering the slick roads, it's taking bumps very nicely.

My problem with 215/40/17 tyres on the front is if I do have the miss fortune to hit a manhole cover or pot hole it's more likely to buckle the wheel as the tyre height is so small.

Looking forward to these turning up now
Think the cars coming off the road for a month, sort rear wishbones and bushes out so I can re attach my rear anti role bar!
Powder coat after adding strengthened drop link mounts
Yeee haaa, nothing like Canning the credit card to make you Keep earning
fk it you only live once

[SILICONEKID345HP]

ClassicChimaera said:

I run my ride height about 5 mm higher than standard and still I've caught the front valance on high curbs etc scratching the feck out of the paint so for road going purposes I'm thinking this is ok.
Cheers for your help Anthony, and others I might add

Only by looking closer at these sizes did I realise on 17 inch wheels my tyres are actually rotating faster than the standard set up (slightly smaller) I wondered why my brakes are so good and it felt lower geared, I'm sure I subconsciously knew

I'd liked to have gone to the 245/45/17 because you'd have a serious gearing uplift and I like the sound of that but I've bottled it

Standard rear Dia 631 mm as opposed to the 245/45/17 being 652 mm so quite an increase.
I have huge torque 345/350 ft lb ( well I think it is ) so think the car would benefit from this higher gearing.

Look at the difference in circumference and you'll see it seems a large change.

Hopefully the fronts which I'm most worried about will fit ok, if they do the business and the rears still can take a larger tyre I'll go for the 245 someday but maybe this is the best balance.
Without delving deeper into the already scary inteweb thing
Y rating I understand the top speed but the 94 or 99 after it,
Does the higher number suggest a harder tyre, a higher load rating, if so then the 245 could be more likely to break away as it has a 99 rating, I'm assuming the 99 would be a firmer tyre wall rather than some compound change?

Edited by ClassicChimaera on Friday 30th December 18:42

Edited by ClassicChimaera on Friday 30th December 18:48

If you are running the same diameter rimsfront and rear I would imagine you would have to make the difference up by having a larger wall height on the rear to achieve the same has using different size rims .

My fronts are 205 50 16 The wall heights look exactly the same which is the target when using different size rims like the standard setup.

Got to admit it 245 45 17 look mean on the back and with a combination of front 215 45 17 you would have a nice setup.
Why not buy one rear tyre and fit on your rim , drop the shock absorber and check to see if everything is ok .
Rears 19 mm higher is less that 10 mm higher wall height .