mark kibort

not that complicated. if you have a finger of space, use the neck of the bat, and hold it down vertically (iIMPORTANT) as to not get a duck billed roll. the idea is to get a straight pushout of the fender or just fold the lip under the fender, depending on how much you need to do. if you had a stock type set up, you could use the fat end. all my rolling, has only used the neck, as most of the fits were REALLY tight. you may also just roll the fender with the bat by hand movement , or have someone in the car , and drive or reverse the car so the bat actually just follows the tire movement and acts like a rolling maching. (except better, really!) keep the bat vertically as much as possible, however, if just rolling the lip, you can use the best angle to get the lip folded under. it may take several small movement passes to get the fender lip rolled underneath, then when you have it pegged back, you can go for flattening it out and some fender pull out too. the steel will stretch quite a long way this way. If anyone has seen my old car, scots 82 or my old 79, we got 315s to fit with no rubbing.

MK

jyoon

"as far as weight, 18s vs 17s, hardly a difference, and even if there was, the tire weighs more, so its actually better to keep less of the weight off the outside of the diameter. meaning, if a wheel weighs 20lbs and a tire weighs 25lbs. its better to grow the wheel and shrink the tire!."

i think a smaller wheel and larger tire will weigh less and be faster. less metal towards the outsides.

mark kibort

the metal weighs more than the aluminum, and you have two sides of rubber that grows, rather than extending the "spokes" of a wheel.
trust me, the weight is more on the tire, not on the wheel.

as far as our needs go, it doesnt make a hill of beans difference. PLUS, ive dynoed 5 lb heavier tires (toyo RA1 vs Hoosier) and on the dyno, no difference!

(and thats 5lbs on the outside diameter!!) yet , rim changes from 17 to 18 is barely measureable. we are only talking .5" on the radius, whether it be a spoke extention, or the tire.

MK

jetrainor

During the switch over from stock 16" rims/tires to 17 twists and Yoko 235/275 rubber, i weighed fronts and backs to see the difference....the new fronts mounted weighed 10 pounds more and the backs were 15 pounds heavier than the stock rim/tire combo..not sure how significant that is but the car still goes like hell.

John Trainor
87 euro silver-black

mark kibort

A little misleading , dont you think????

sure, i went to 17s as well and the rim weight jumped 10lbs wheel!! its not the diameter, in these cases, its the WHEEL TYPE < Material and constuction.

now, i have 18s and they weigh less than 15" stock wheels. so what. the point is APPLES to apples, keeping overall diameter the same (ie tire and wheel) there is no diff going up in diameter as far as rolling weight. all of my same manufacturer wheels of 17 vs 18s of the same sizes and widths, weigh the same. BUT, i bet the 18s have less of the weight on the outside diameters, due to less tire. think about how much 2 1/2" strips of tire rubber 80" long (ie 25 "" diameter X Pi) vs the rim center that is 1" diameter more. rubber weighs more than aluminum.

MK

jyoon

imho i think the aluminum in the wheel rim and metal in the tire beed will be greater in a larger wheel/tire and more than offset the increase in weight of the larger sidewall (in the smaller wheel/tire combo) resulting in a larger wheel/tire combo to be heavier and have more weight towards the outside.

jetrainor

Mark....not trying to make a point, just passing along what i thought might be an interesting weight comparison...i could care less about the difference in weight because the new rim/tire combo has given me a new ride that i'm having a hard time keeping my eyes off of....my wife is at the 'rolling her eyes' stage so probably dinner out is in order....it may also have something to do with the 900 Triumph triple i just added to the garage....black/black chrome - 100 hp at the wheel, but as i explained, its a two-up so she can come too!

jt
87 euro auto silver-black

Garth S

jetrainor,
You have, via your data, touched on two issues that are both valid principles and axioms of fast cars - and women.
Firstly, to minimize unsprung weight always enhances handling: that works for both categories above.
Secondly, expenditure of discretionary household funds on fast cars can only be offset by fine dining and wine at some establishment far beyond the home - or you fast track to the doghouse ....
The serious part, of course, is that all other things being equal ( tire diameter, width, compound, etc), the lower weight assembly (unsprung mass) will always be better controlled by its spring and shock - and better respond to maintaining its contact patch firmly against the track during all vehicle dynamics.
Going fast in a straight line is less critical of the important point you raised

mark kibort

well, its not the case. 18 vs 17 hoosiers weight close to exactly the same (+/- a couple of ozs) 18 " and 17" kenesis wheels of same style are close to the same weight.
the wheel and tire both 17 and 18 are amost the same weight together.
the differences are so small that its really not worth discussing. (ie in the oz range, not lb)

so, thats solved now. (unless someone has differerent weights for same type of wheel and same brand syle of tires of different sizes)

MK

mark kibort

yes, but if the wheels and tire is the same weight then there really is no gains. in fact, ive just stated that there is no real difference (very very small , if any)

Ive stated why there is no real difference as well

Plus, ive tested a pretty extreme case of having 5lbs more tire (worst case by a factor of 10 vs any possible rim change ) and i saw no difference in my times or handling on some of the worlds most demanding tracks.

so, who you gonna believe. Mr tire rack and the marketing BS, that is truely BS in more cases than not, or folks that have some pretty controlled data and performance results?

17" kenesis with hoosiers front 44lbs rear 46lbs
18" kenesis with hoosiers front 44lbs rear 46lbs
18" kenesis with toyo RA1 front 49lbs rear 51lbs
rear kenesis 20lbs front kenesis 19lbs (thats 9.5" vs 11" which is MUCH more mass than just making a rim 1" larger diameter. heck, you can tell by looking at a 11 vs 9.5" rim which is bigger, but its pretty hard to tell a 18 vs 17" rim of the same width unless you look closely.)

imho

MK




Mk

Rob Roy

Since my budget is rapidly getting depleted, I was thinking about something like these on my widebody project until I can buy my ultimate choice. They are cheap knock-offs, but would at least get me on the road for a while. Not sure how these offsets would work on a widebody though.

http://cgi.ebay.com/ebaymotors/ws/eB...category=43958

mark kibort

well as was said, you need 1/2" more radius in the spoke area and a strip of metal in the outer rim circumference that would be 3" by 9.5" . that much aluminum doesnt weigh very much. even if you took the straight percentage of size (diameter) and multiplied it times the diameter diff, you get 1.06. since we are not changing the width, divide that by 2. now, 3% would make a .6lb differnce on a 20lb rim. hardly worth mentioning. Now, minus any material you remove from the tire, and you have the net difference. a .5" strip of rubber 13 feet long will weigh somthing, what do you think? heck, i have weather stripping from the race car that weighes more than 1lb and its not even 13ft long.

you see, you probably get gains by going to 18 vs 17s as long as the outer tire diameter stays the same or close. Bottomline the diff is so small, its hardly worth mentioning, and certainly doesnt come near being a factor in handling.


Mk