Same size wheels

hiscot · Post by **hiscot** » Mon Apr 23, 2007 4:59 pm

Anyone running same size wheels front and rear ie 15 or 16 ect
any reason why not , any advantages / disadvantages

Lazydonkey · Post by **Lazydonkey** » Mon Apr 23, 2007 5:33 pm

All VX's have 17" all round, as do the new Europas.

Only disadvantages I can see is that the fronts are a darn site heavier than ideal and you can't get many 175/45 17" tyres to fit. Well there is only one to be honest.

I'm sure someone who knows something about some things will be along soon..........

r10crw · Post by **r10crw** » Tue Apr 24, 2007 7:50 am

Bob, It recommends in the manual that you put 15s (S1) on the back in snow which makes sense but as for the front on to 16s I cant see any advantage. Cheers Craig.

tuscan_thunder · Post by **tuscan_thunder** » Tue Apr 24, 2007 2:02 pm

I would think 16s on the front would limit suspension travel and stop you being able to run it so low?

Post by **Shug** » Tue Apr 24, 2007 4:12 pm

In design terms, the 15/16 thing was purely for styling. The engineering bods nearly had it on 13s at one point! (unsprung weight reduction)

tuscan_thunder · Post by **tuscan_thunder** » Tue Apr 24, 2007 4:15 pm

..which is partly the reason why my hillclimb saxo will be sticking with 14inch wheels - lighter, car can be lower to the ground without hitting bump stops, lower gearing, cheaper tyres. win win win win situation!

hiscot · Post by **hiscot** » Tue Apr 24, 2007 6:31 pm

tuscan_thunder wrote:..which is partly the reason why my hillclimb saxo will be sticking with 14inch wheels - lighter, car can be lower to the ground without hitting bump stops, lower gearing, cheaper tyres. win win win win situation!

caterham use small wheels , i understud it was because of the gyro effect a spinning wheel has

but wondered if for track use why not 15" all around ?

also heard fitting 15/16 after marketwheels to a S2 transforms it ie better gearing but have read they also corner better , dont know if its true

yet s1 exige has the larger wheels

Post by **Shug** » Wed Apr 25, 2007 9:51 am

It's always a trade-off.

Larger wheels give you more space for big brakes (and fill the arches on the Exige, which was developed from the Motorsport racers, which did have bigger brakes to accomodate) They also let you use short sidewalls, making the tyre contact patch more stable and taking out some of the undamped suspension factor of the tyre.

Smaller wheels give you less unsprung weight & less weight overall. As they are on the 'wrong' end of the suspension, extra weight there means that you have less control using the suspension as the mass of the wheel/tyre combo has to be controlled.

F1 tyres are 13" with mahoosive sidewalls purely because the rules state you need a 13" max rim. Keeps brake sizes down. Side effect is that as much as 50% of the suspension movement in a current F1 car is down to the tyre sidewalls.

Post by **Shug** » Wed Apr 25, 2007 9:53 am

Oh, and using a 15" rear wouldn't really work on the elise, as the suspension geometry is set up for a 16" rim (and relatively large sidewall) to get the correct ride heights. Raising the suspension to compensate would throw out the dynamic camber and bump steer etc...

Rich H · Post by **Rich H** » Wed Apr 25, 2007 9:57 am

I'm suprised that smaller wheels save much weight, but that's because I haven't thought about it until I started typing this. I've answered my own query now.

Move along nothing to read here.....

(I've just realised that bigger wheel = lots more rim and a little more wheel face. The weight of the extra rubber in the sidewall is minimal in comparison to an extra few inches of rim)

Who will be the first running 13" mini-lites and carbon-ceramic brakes then?

Tom · Post by **Tom** » Thu Apr 26, 2007 10:35 am

i asked my lecturer this question, and he went away and found an answer. it's something along the lines of it has an effect on the suspension geometry which helps the elise sustain around 1G of lateral grip, something which i gather is helped by having smaller wheels on the front.

HTH