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Has anyone noticed how the tyres fitted to F1 cars have an aspect ratio of approx 50%. You cant tell me that F1 teams dont know what they are talking about. Seems to me that Toyota got the tyre wheel combination ie: 15 inch with 55/50% aspect ratio pretty spot on...But When I'm Very Very Old!
Poohbear wrote:Hya,
Just to add my twopenneth to the debate.
Bob
£1000 each and are made specifically for each car, to mass produced junk thats made to fit as many cars as possible and work in cold/hot/wet/dry conditions. I.e, the wheel rim size and tyre widths are constrained. I seem to remember Damon Hill testing low profile tyres in a Williams back in the mid nineties, however the FIA seemed to think that the cars were going around corners fast enough as it was and changed the regulations to stop teams developing them any further. Unfortunately for us, the MR2 seems to struggle 
.... 
i tried to follow one of those atom things round a roundabout one day..... except... And to the dismay of my konei's and advans (7.5"F & 8"R) with 215/225 45 (toyos) 16".... i watched it accelerate off into the distance. 
Alex_Dunn wrote:if its true smaller wheels give better handling why do ferraris and porsches have such big rims?
..jonno wrote:Alex_Dunn wrote:if its true smaller wheels give better handling why do ferraris and porsches have such big rims?
Have you read ANY of this thread?
... Go back to page 1 and start again from the top!Speedy wrote:jonno wrote:Alex_Dunn wrote:if its true smaller wheels give better handling why do ferraris and porsches have such big rims?
Have you read ANY of this thread?
Indeed.
Cars handle best on the wheels and profile tyres they were designed for and that the suspension geometry can cope with.
NOT the right answer ... people have spent a lot of time posting to threads like this - do them the courtesy of reading their posts before posting like this 
BenF wrote:
"slip angle" on the the low profile tyres. 
tonigmr2 wrote:Fear me, for I am watching
- thanks everyone - really useful!- looking at touring cars for example, you see many commonly available hatchbacks/saloons racing using larger wheels than stock, and not all teh teams run in classes where the entire setup is reworked - indeed - you see a wide range of alloy wheel sizes available across the range from the showroom and I doubt very much that they make much effort to change the suspension setups. So how do we know for sure that every package is designed to be the optimum - and if not, just what is?.. And at the time the MR2 was built, 15" was considered a big alloy wheel - so it fitted into the cost constraints of the package at the time. Given that we accept a Boxter runs MacPherson struts and happily runs very well on 18's, is it not fair to assume that an MR2 with some additional suspension development *could* run better on larger than stock sizes? .. 
looking at touring cars for example, you see many commonly available hatchbacks/saloons racing using larger wheels than stock, and not all teh teams run in classes where the entire setup is reworked
If you're talking about 750mc Stock Hatch, they run standard rim and tyre combinations, and their suspension is a lot stiffer (and the car is as well, once you put a roll cage in).indeed
- there will be a designed in range of wheels. Having said that, our old Focus had larger profile tyres than our new one, and you can certainly notice the difference..Given that we accept a Boxter runs MacPherson struts and happily runs very well on 18's, is it not fair to assume that an MR2 with some additional suspension development
"boxster has struts, therefor anything which the Boxster can do, the Mr2 can do as well" - even with some 'development', there are lots and lots of variables which come into play, the stiffness of the chassis, the unsprung weight, the weight distribution of the car, the compliance in the suspension, ride, as well as the fundamental geometry of the system, which is pretty hard to alter.If all it comes down to is the ability of the car at 10/10ths to remain pointed where it needs to be, is it more down to driver skill or the car setup?
If you are driving at 10/10ths (or beyond) then it's up to the driver to keep it pointed in the right direction. A more agressive setup (with wider section tyres and lower profiles) will make it harder to drive quicky, because the car will let go quickly.I guess what I'm saying is, given a choice of any off the shelf components currently available, could an MR2 be set up that would be faster with 18's than it could be with 15's? I don't for one minute assume it would be a nicer driving experience, but simply that it might be faster? And in turn, just how much copst would we be talking to get to that point.
- without even thinking about handling.What did the TRD or SARD MR2 racers use given a racing team budget to set them up?
tonigmr2 wrote:Fear me, for I am watching
(rev 2 ) upgrade was to accomodate the bigger brakes, but it was also to shut up the early complaints about wayward handling of the rev 1. I think geometry, anti roll bar mods and the 15" wheels with Yokos instead of bridgestones were the sum of the 'upgrade' from rev 1 to 2, though don't quote me, and i'm sure someone will be along to correct me if i'm wrong; my memory is not all that good anymore...... 
- what Toyota saw fit as the ultimate result of all that expensive initial R&D wasn't actually the best setup. So when people say that xyz manufacturer spent all that money getting the best possible package isn't necessarily fact. It's more appropriate to say its the best cost compromise within any given design brief - they'll ultimately be working to a budget - and large wheels, more expensive suspension, bigger brakes etc etc doesn't always figure in the budget allowance. Thus a car is launched with wheels smaller than what could be potentially the best possible set up.- and it may be that the MR2 really is at it's best on 15's, but give Toyota another 2-3 grand on the retail price of the MR2 (reasonable given what we often spend on wheels,tyres and suspension compenents in the course of modifying) and ask them to do the work again now and I wonder if it would still have 15's?matt_bakermk1 wrote:Hi Ryan,
That was kind of exactly why I made the comment
This is all very much speculation
( I think the brakes are also fitted to the Carina but maybe the rears are not vented! ).(n/a spec), there was some disagreement over whether there were really 'problems' when looking back at old issues of test mags........ 
.. few months later, they decide to shove in the turbo engine - handling now not quite right for extra torque, so toyota bods have to make the car a bit 'safer' by modifying roll bars etc for the rev2.- and weren't most of the changes down to press guys who couldn't cope with the handling on the limit?(read race drivers) actually preferred the early revs handling traits as it was a more involving experience? I found with the very low and harsh ride it makes driving in the wet even more of a nightmere. I also get alot of bounce on the tyres due to the lack of movement in the suspension., to me this is a good thing . , the camber value is increased . , because if it didn't , the contact patch of the tyre would be more on the outside edge of the tyre , due to tyre deformation . The increased camber value , allows the tyre to have a fuller width foot print ., the wish-bones are unequal in length , this has the effect of increasing the camber value , under compression , just like the MacPherson setup . , so I went to the tyre shop . When I got there I had the correct size tyres fitted to the rear , instead of fitting the correct sized tyres to the front , I fitted ones with a lower aspect ratio (195x50x15 instead of the correct size 195x55x15) , because they were cheaper 
., this introduction to oversteer was a real eye opener to me and taught me to respect this car like no other before ., and to say the car was transformed is an understatement ., I wouldn't have believed it if someone had told me . With the right sized tyres the car has become very predictable and an absolute joy to drive on the ragged edge , it doesn't scare me any more and is easily balanced on the throttle now .(LSD) , bog standard + K&N panel .