Tyres and sidewall heights
Discussion
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.
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 said:
235 45 17 Rear and they look spot on .
Fronts are 16 "
Yes they do.Fronts are 16 "
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
Richard 858 said:
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
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.
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 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. 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.
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 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 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
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
f
k it you only live onceWhat width is your front wheels Daz 7.5 ?
". ". ". " Rear wheels 7.5 or 8 inch.
Goimg by the calculator I'm using and assuming a 7.5 front wheel
Your 205/50/16 are 611.4 mm outside diameter so only 4.9 mm larger than standard 205/55/15 tyre size
Your rears are 643.3 mm so 11.9 mm bigger than the standard 225/50/16 with a 631.4 mm outside Dia.
A very good set up
It's the high 99 rating that put me off the 245 tyre Daz, it's a big old tyre normally holding up a heavier car,
Bigger is always better on track cos you can lean allover them but for everyday use I think the 235 is more suited. And yours looked the boolox + you did a blinding time on them there babies. Can't wait
I've got to get under 13 seconds on the strip
". ". ". " Rear wheels 7.5 or 8 inch.
Goimg by the calculator I'm using and assuming a 7.5 front wheel
Your 205/50/16 are 611.4 mm outside diameter so only 4.9 mm larger than standard 205/55/15 tyre size
Your rears are 643.3 mm so 11.9 mm bigger than the standard 225/50/16 with a 631.4 mm outside Dia.
A very good set up
It's the high 99 rating that put me off the 245 tyre Daz, it's a big old tyre normally holding up a heavier car,
Bigger is always better on track cos you can lean allover them but for everyday use I think the 235 is more suited. And yours looked the boolox + you did a blinding time on them there babies. Can't wait
I've got to get under 13 seconds on the strip
Edited by ClassicChimaera on Friday 30th December 21:20
QBee said:
I am not sure why you are worrying about buckling wheels.
My Saab 9-5 runs on 235/45 17 tyres (Rainsprout 3s) and nobody has suggested I will buckle the wheels - they are standard fit on these cars, and Saab are /werevery safety and build quality conscious.
I have been on 40 or 45 profile tyres for the last 30,000 miles on 17 inch rims with no problems.
It might have something to do with the buckled wheels I've had, one pot hole on Peters old rims flat spotted and cracked the rim, needed serious repair and was almost scrap, 205 width mind! Pothole was a big one though! etc etc. Ffs My Saab 9-5 runs on 235/45 17 tyres (Rainsprout 3s) and nobody has suggested I will buckle the wheels - they are standard fit on these cars, and Saab are /werevery safety and build quality conscious.
I have been on 40 or 45 profile tyres for the last 30,000 miles on 17 inch rims with no problems.
Even these Azev wheels on Toyo T1R tyres with a 215 width and 40 height I've had similar experience.
The tyre looks stretched over the wheel and my rim is almost wider than the tyre. Easy to scrape on a Cerb for instance.
I've noticed on one site it says you shouldn't fit bigger than 235 on a 7.5 inch rim, I've got 245 at the mo, to be honest it looks like it fits better than the fronts do.
It's not hard to see when looking at pictures by having 17 in rims on the front and a tyre size that mimics the original outside Dia it will be a very shallow tyre.
I've never got on with low profiles, ok there more stable at speed etc but everything else they just ruin your comfort and ride.
I like big old tyres, I think it also suits the car better, I just hope by taking the front size up by 18.8 mm from the standard 606.5 mm Dia to 625.3 mm I won't induce to much understeer.
The front wheels are going to be turning slower so will it effect the brakes and how much the tyre heats up.
I'm getting all F1 on it
If I have a higher rude height I could make a bigger splitter
I'm not worrying Anthony, just over thinking it a bit, keeps me out of trouble and my mind free.
Tvr changes and upgrades are a bit of a joy in difficult times.
Gives me motorvation,
Having looked at others cars as maybe a replacement for the Tvr during the summer and realised I've got the best car for the buck,,,, on the planet it's easy to commit to its continued path of hopefully improvements.
I realise more and more how lucky I am to have a car so worthy of such things.
Tvr rock like few others
SILICONEKID345HP said:
I allso have the 308 diff ratio.
Yeah and your really funny !! I forgot to mention, you better watch your speed through cameras
As if I've got this right you've got a lower reading at 30 mph on your Speedo, more like 27 mph with all your changes considered.
The circumference of your rear tyre is 37.4 mm bigger than a standard tyre. That's if my math is correct.
That's a long distance per turn of the wheel when you think about it so adding to your higher gearing
You star you
RobXjcoupe said:
Above looks a bit blurred but option front tyre size is a 225 50 15 on a 7" front rim. People are forgetting to mention wheel offsets play a big part if wheel and tyre combinations will rub or not
Now your taking me into a whole new level of hurt! Offsets, my brains just fused!
Ok to try and narrow mine down a bit I'm using
17 inch AZEV rims allround with markings as thus
7.5J X 17 H2
Help!
I'm off to bed as I'm up early,
Can anyone confirm what my offsets are and what standard should be please.
2OOM said:
I think on std wheels it's 15 inch 7j et25 front and 16 inch 7.5j et 33 rear .. I've put 16 inch imola wheels on the front and I have 205/50R16 on the front and 225/55R16 on the rear ..
Excellent cheers for that Graham. I'll do some re calcs as I've mainly been talking about tyre diameters it shouldn't make a difference with 1/2 inch difference. Offset yes but I'm not far from standard so it should just work, famous last words.
If anything I'll either just need to raise ride height a tad or use some spacers if I have wishbone or body rubbing, full lock there's a risk they will contact the inner wing so we'll just have to wait and see.
2OOM said:
I used Mr Gasbag's suggestion for tyre sizes and they have worked well for me,the taller profile has smoothed out the ride a little.
I am probably staring at the wrong end of the stick with this thought but when you have a 20mm larger diameter, I've always thought of it as 10mm at the top and 10mm at the bottom of the tyre so to speak .. so the tyre will be 10mm higher into the wheel arch ..
I worked out the size then used my tape measure across the tyre, and yes it's about 10mm wider than the 40 profile tyre per side I am probably staring at the wrong end of the stick with this thought but when you have a 20mm larger diameter, I've always thought of it as 10mm at the top and 10mm at the bottom of the tyre so to speak .. so the tyre will be 10mm higher into the wheel arch ..
Nice pics guys, that's more like it.
RobXjcoupe said:
TVR original spec sizes for wheels and tyres is the bit for people to view. Note the front tyre size option if power steering is fitted
Oh yeah,,, Pas 225/50
It's the 225 that's interesting as you say.
That's thrown me!
I Better no try calculating it now mind,,,,
Yes correct, where did I pull the 15.5 larger Dia from!
I've got a piece of paper with so many numbers scribbled allover it you'd think it was my accounts...
If I wanted to keep the tyre size in proportion to each other id be going fo something like
215/45/17 = 625.3
245/45/17 = 652.3
These are both about 20 mm bigger than a standard tyre front and rear so theoretically my ride height wouldn't need agjusting but then the Y rating is higher so I'd assume a firmer tyre wall, I don't want that!
I've got a piece of paper with so many numbers scribbled allover it you'd think it was my accounts...
If I wanted to keep the tyre size in proportion to each other id be going fo something like
215/45/17 = 625.3
245/45/17 = 652.3
These are both about 20 mm bigger than a standard tyre front and rear so theoretically my ride height wouldn't need agjusting but then the Y rating is higher so I'd assume a firmer tyre wall, I don't want that!
hillclimbmanic said:
Oops...My bad.!!
I've just checked...215/40x17 =1821.02 mm THAT'S what I've fitted...
Verses: 205/55x15 =1829.16 mm
Plus I've fitted 10mm spacers, and Ford Motorsport studs, to clear the big discs and Brembos...
Rear: 225/50x16 = 1904.26 mm - 245/40x17 = 1893.4
ETA by Al !
Fronts
The calculator I'm using suggests
205/55/15 = 1905.4 circumference 606.5 diameter
215/40/17 = 1896.9 mm 603.8
Rears
225/50/16 1983.6 631.4
245/40/17. 1972.3. 627.8
Essentially both front and rears are smaller than standard. This is the set up I have at the moment.
I've just checked...215/40x17 =1821.02 mm THAT'S what I've fitted...
Verses: 205/55x15 =1829.16 mm
Plus I've fitted 10mm spacers, and Ford Motorsport studs, to clear the big discs and Brembos...
Rear: 225/50x16 = 1904.26 mm - 245/40x17 = 1893.4
ETA by Al !
Fronts
The calculator I'm using suggests
205/55/15 = 1905.4 circumference 606.5 diameter
215/40/17 = 1896.9 mm 603.8
Rears
225/50/16 1983.6 631.4
245/40/17. 1972.3. 627.8
Essentially both front and rears are smaller than standard. This is the set up I have at the moment.
Edited by hillclimbmanic on Sunday 1st January 16:18
Edited by hillclimbmanic on Sunday 1st January 16:30
Edited by hillclimbmanic on Sunday 1st January 16:32
Edited by hillclimbmanic on Sunday 1st January 16:41
hillclimbmanic said:
I quoted from: Wheel and Tyre Bible...Sorry if they're wrong.!!
Paul
I wouldn't know which is correct, just pointing out the slight difference, looking at your post again and using the calc Paul
You appear to be suggesting the rear 245/40/17 is 1893 which looks like a slight mix up on the 225/50/16 1983
But then I could have easily mixed up a few numbers when writing it all down
I'm known to do it when half cut It's a few mm here or there anyway, if they fit in there as Qbee says those with adjustable suspension can dial out some difference.
The Rainsports that I've seen appear to have a soft sidewall as well as soft tread blocks, I'm hoping I can play with tyre pressures a bit more as the higher tyre wall allows me greater scope.
The 215/40/17 on my car as the size suggests, has a very low side wall and causes me to bottom the tyre out and the rim edge takes the strain, I'm trying to soften the car more for localised speed limit restricted driving, I have other wheels I might put some summer rubber on but for now I'm looking at the ride and comfort level for the easy drives I tend to actually do. It's not that often I'm ripping it up, and if I am I'm puffed out in seconds so we go back to sleepy mode.
How many of us actually hoon about. If I get better grip this way for slow road based use and can protect my electrics by taking up more of the bumps,, I'll be into the car more.
It's not hard to change one of these cars with sets of shocks and wheels from race b
d tough guy to old fart softie. I'm liking old fart softie at the moment
Nearly forgot to mention, nice chassis and that wheel is just simply showing off, lovely
Edited by ClassicChimaera on Sunday 1st January 21:20
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