blakep82
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| posted on 2/11/12 at 01:23 AM |
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how to choose tyres and speed ratings for IVA?
ok, i'm still all out of money, and i'm still not sure what size tyres to go for.
I got a set of wheels with 265/50R15 tyres, and the edge of the tyres catches the front bumber, wheel arch and part of the chassis when you steer, so
thats no good. I'm sure its an 8.5" wheel, but i've not got a reliable way to measure (it probably says on the back of a spoke or
something, i just haven't looked yet, as thats quite a job in itself at the minute.
so, the current tyres, which are bald anyway, are too wide for the rims, i know this already. I need something narrower, and slightly smaller in
diameter. I'm thinking 225/50R15? but i'm not 100% sure this is right yet til i try some.
I've seen some part worns on ebay i could try, Fulda brand ones, about £70 for 2, delivered, which is ok because i can't afford a full new
set, and can't risk them being wrong anyway, and they would be ok for IVA if they fit right. if they do fit though I'd want to get some
Toyo T1R's for the other 2 wheels.
so here's the thing, is an IVA tester likely to be unhappywith different brands on the front and back? say Fulda on the front, Toyo at the back?
then the next question, Fulda have a speed rating of Z - 150Mph+, Toyo have V - 149Mph
what should my speed rating be? how do i work it out?
those speed calculator things say top speed of about 200mph with my gearing, but doesn't take into account wind resistance
SHP's website say they race at 140mph, and have more powerful engines than mine,
so, how do i measure it?
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IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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daviep
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| posted on 2/11/12 at 09:14 AM |
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In reverse order.
For IVA as long as the speed rating of the tyre is faster than the declared top speed then everything is OK. Obviously use a sensible top speed figure
and if you are running V or Z rated tyres you will be quite safe.
Inspector can't complain about there being different brands of tyre, it doesn't look proffesional which may cause him to look at your
build a bit more carefully,but he cannot it fail it for that. You can use differnt size tyres front and back without a problem, so if you have two
legal tyres already you could put them on the rear.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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matt_gsxr
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| posted on 2/11/12 at 02:26 PM |
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IVA maximum design speed is either an educated guess, or is maximum RPM in top gear.
So in your case we guess.
Based on 200bhp and aero of a brick you might get 130mph.
Looking at the speed ratings you might arouse suspicion with an H-rated tyre (130mph), but V-rating is 240kph (~150mph) which gives you loads of
headroom.
Normally you can get part-worns supplied and fitted at a reasonable price.
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blakep82
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| posted on 2/11/12 at 11:26 PM |
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awesome, cheers lads, i'll stick with my top speed being 130mph then, kinda what i guessed too, based on races being run at 140mph
i'll keep those Fulda ones in mind as a possibility though, they're cheap enough for the 2, just can't really see them before
buying
tried the scrap yard today to see if they had any, no luck, but the guy said he'll leave some outside the back of my work if he has any come in.
will try the tyre shop tomorrow morning too, see if they've had one in at all, just to try for size, so i know
if no luck then i'll get the 2 fulda ones off ebay, and later get some toyo ones then. i'd prefer all the same, but we'll see if i
got the money later
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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