Alloy wheels!

[chiz]

I am what I think you call a newbie and have just purchased a 1988 t3 van, although I was a splitty owner a number of years ago. Anyway a simple question I think. Other than the improvement in looks when alloy wheels are added to a van are there any economical benefits? I mean with bigger rims and lower profile tyres do they run more efficiently? My other question is if the previous questions answer is yes how big can you go and what is the spec and mods needed please?

[t25adict]

depends on what the van is for, the standard tyres/wheels are fit for the job they do..
economy wise the general idear is if you fit wider tyres it will make more drag... ie worse for economy... but no more difference than the wrong tyre pressure ect..

if you want an improvment in drive then wider tyres like for eg a 16" alloy with 205-55-16 tyres is ideal... plus in that size the tyres are at good prices as half the modern vag group cars use them..

with fitting alloys to a van you need a good quality alloy wheel as higher loads than car use are put on them..
also you wont realy get any wheel/tyre setup with a lesser weight than the orignal 14" setup in general.. alloy wheels that are good for use on our vans aint often much lighter than the steel wheels/tyres they replace.

as to max size... 18" is it realy to keep within the orignal rolling diameter tyres wise.. but thats big money..

the easiest alloy wheels to fit to a t25/t3 are granada 16" ones as the pcd is 5x112 the et/offset dosent need spacers and the 6.5" width rim dosent cause probs with the body. (and they can be found cheep)

OE. carat 14" wheels are good but normaly sell at a high price.. and arnt all that comon.

[Anonymous]

Just a note here, if you fit 205/55/16's you are fitting smaller overall diameter wheels and tyres so your engine will be reving higher for the same speed.

Tyre size calculators are all over the internet but its really very easy to work out.

If you look at your tyre, the numbers on the side tell you all the infomation (well almost!) you need.

185/14 is a 185/80/14.

The 80 is a measurement of the profile (the sidewall height) and it is a % of the width.

So a 185/80/14 is 185/80 = 14.8cm.

Then the 14 is the wheel diameter in inches (seems very silly to have metric and imperial on the same thing doesn't it!).

So 14 inches (25.4mm = 1 inch) is 35.56cm.

Taking into account that you use the profile twice (as its there top and bottom on the wheel), add all that up and you end up with the overall rolling diameter of 65.16cm.

If you wanted to fit 16 inch wheels, 205/60/16 would be slightly bigger at 65.24cm but you're not going to notice 0.08cm!

Without wanting to start a fight here (!) there is a very useful thread on Brick-yard for wheels which will fit without too many problems.
http://194.242.159.246/brickyard/forum/ ... D=596&PN=1

MG

[HarryMann]

seems very silly to have metric and imperial on the same thing doesn't it!

Exactly, they should have stuck with pagan units and then we'd know where we are

In fact, if you want to get real accuracy, say for determining the exact change in gearing, you need to compare the TRCs, True/Tyre Rolling Circumference, which never works out to Pi*D, as the tyre doesn't roll as true circle - Michael's method gives you a good first stab though, and those TRC calculators mentioned can be notoriously inaccurate - ultimately, look for a manufacturer's TRC figure (for actual speed/revs) or roll the vehicle and measure distance over 10 revs say (only for comparison one with another).

Larger wheels and tyres also affect acceleration and braking, if they have a higher mass moment of inertia (are heavier at the outside or larger). Because these have to be accelerated rotationally, and there's 4 of them, much larger wheels and heavier tyres can start to be noticed. And larger ones have to be braked as well as the vehicle mass. This is one reason why the Syncro 16" was fitted with LT brakes.

[t25adict]

ok yes your right mr Harlequin Syncro, the 205 60 16 is closer
185-14-C (80%) = rr of 651.6mm
205-55-16. = rr of 631.9mm
205-60-16. = rr of 652.2mm

i picked the 205-55-16 as its often what comes on wheels that have 5x112 pcd fitment (lots of vag stuff) as dose the 215-55-16 (rr 642.9mm)
going with the economy bit as partly touched on in the first post the 205-55-16 is cheeper to buy, often comes in fuel tred save paterns,and often comes part worn on wheels good foe vdub vans.

also the 205-55--16 is ONE OF the stated conversion sizes on the yoko Rolling Radius chart i use (when i cant be bothered with the calculator)

as to the "picking like a hen" last coments/corrections... if you realy need to quote text book stuff at people then you must have to much time on your hands..

TRCs is why i use a tyre manufacturers conversion chart... yes it can be calculated down to the last tiny bit.. but im just here trying to help somone not pic at the coments of others.. (no offence ment to mr HS. a just coment made )

can see why some are tired of being on here at times

[HarryMann]

TRCs is why i use a tyre manufacturers conversion chart... yes it can be calculated down to the last tiny bit..

Well that's the point isn't it, it can't, actual TRCs quoted by mfrs are established empirically

... and since part of the question was about economy, mentioning that change in wheel and tyre size has other effects, rarely acknowledged, maybe of help. Don't think you'd find that in any textbook either

Tyred of being on this forum,

is there a pun there?

[chiz]

Yes well I am obviously a complete novice and have loads to learn on the subject of wheels. Thakyou for all the input. I think!

[HarryMann]