NB's Show Off Your Rims!

[Hjt]

Not to poke fun but genuine curiosity, how much work have you done to your SE to make it 170rwkw. That's close to 200kw at the flywheel. Must be running atleast 12 psi, larger injectors etc.

[Apu]

There is so much bullflop written about rims and tyres

Finally all this lightweight rim crap. The unsprung weight totals wishbones, springs, shocks, hubs, brake disk, calipers, lines, wheel nuts, rubbers, tyres, air in the tyres and god knows what else, within this is also the weight of the rim. The diff between 17" Racing Harts 7+ kg vs a 5+ kg 15" is trivial.

I had the racing Harts and they were far better in all respects to the 16" stock. I would get 6uls because they are a well made, well priced rim which also looks classy. Nuff said.

Largely right but this would apply more to a turbo car. For an N/A MX5, the 2-3kg difference would be felt. I dropped back from 16" to 15" and saved nearly 3kg - the car is more responsive from a steering and acceleration point of view.

It does take more effort to get a heavier object to move and change direction. However, what is more important is where the extra kgs are...weight at the hub? Or more weight at the edge of the rim? That's why one 6kg wheel is better than another 6kg wheel.

[slimx]

i got a question for you lot, is there way to use VERY VERY low profile tyres and some how make it more comfortable in my opinion seriously ANY RIM looks good any size, long as it has super thin tyres, but ofcourse issue with this is the ride comfort.

Is there a type of tyre out there.. or maybe a special way other than "suspension related" im talking potholes etc..

[devski]

i got a question for you lot, is there way to use VERY VERY low profile tyres and some how make it more comfortable in my opinion seriously ANY RIM looks good any size, long as it has super thin tyres, but ofcourse issue with this is the ride comfort.

Is there a type of tyre out there.. or maybe a special way other than "suspension related" im talking potholes etc..

lol.

[Charlie Brown]

i got a question for you lot, is there way to use VERY VERY low profile tyres and some how make it more comfortable in my opinion seriously ANY RIM looks good any size, long as it has super thin tyres, but ofcourse issue with this is the ride comfort.

Is there a type of tyre out there.. or maybe a special way other than "suspension related" im talking potholes etc..

Short answer, NO.

Long answer, the lower the profile the less the sidewalls can absorb the bumps.
Mind you the wider the tyre with the same aspect the more side wall depth. ie a 215x45 has a side wall depth 0f 97mm where a 195x45 has a depth of 88mm.

[Aussie Stig]

There is so much bullflop written about rims and tyres

Finally all this lightweight rim crap. The unsprung weight totals wishbones, springs, shocks, hubs, brake disk, calipers, lines, wheel nuts, rubbers, tyres, air in the tyres and god knows what else, within this is also the weight of the rim. The diff between 17" Racing Harts 7+ kg vs a 5+ kg 15" is trivial.

I had the racing Harts and they were far better in all respects to the 16" stock. I would get 6uls because they are a well made, well priced rim which also looks classy. Nuff said.

Largely right but this would apply more to a turbo car. For an N/A MX5, the 2-3kg difference would be felt. I dropped back from 16" to 15" and saved nearly 3kg - the car is more responsive from a steering and acceleration point of view.

It does take more effort to get a heavier object to move and change direction. However, what is more important is where the extra kgs are...weight at the hub? Or more weight at the edge of the rim? That's why one 6kg wheel is better than another 6kg wheel.

What, 3kg a wheel going from 16 to 15 ?
Surely thou art shooting a line, or you had some mighty boat anchors originally, get a pic of them here so every body can avoid them

[PaulF]

There is so much bullflop written about rims and tyres

Finally all this lightweight rim crap. The unsprung weight totals wishbones, springs, shocks, hubs, brake disk, calipers, lines, wheel nuts, rubbers, tyres, air in the tyres and god knows what else, within this is also the weight of the rim. The diff between 17" Racing Harts 7+ kg vs a 5+ kg 15" is trivial.

I had the racing Harts and they were far better in all respects to the 16" stock. I would get 6uls because they are a well made, well priced rim which also looks classy. Nuff said.

Largely right but this would apply more to a turbo car. For an N/A MX5, the 2-3kg difference would be felt. I dropped back from 16" to 15" and saved nearly 3kg - the car is more responsive from a steering and acceleration point of view.

It does take more effort to get a heavier object to move and change direction. However, what is more important is where the extra kgs are...weight at the hub? Or more weight at the edge of the rim? That's why one 6kg wheel is better than another 6kg wheel.

What, 3kg a wheel going from 16 to 15 ?
Surely thou art shooting a line, or you had some mighty boat anchors originally, get a pic of them here so every body can avoid them

Probably 3kg over all 4 wheels - or, as you say, some serious anchors for 16's.

[Lokiel]

:
Finally all this lightweight rim crap. The unsprung weight totals wishbones, springs, shocks, hubs, brake disk, calipers, lines, wheel nuts, rubbers, tyres, air in the tyres and god knows what else, within this is also the weight of the rim. The diff between 17" Racing Harts 7+ kg vs a 5+ kg 15" is trivial.

I had the racing Harts and they were far better in all respects to the 16" stock. I would get 6uls because they are a well made, well priced rim which also looks classy. Nuff said.

17x7 Racing Harts are a WHOPPING 8Kgs!
15x8 6ULs are around 6Kgs.

That's an extra 2kg per wheel of rotational mass, 16kg in total, that needs to be slowed/stopped when braking or sped up during acceleration. It does make a noticeable difference with smaller brakes and less horsepower but also means that my "uber-5" SE (ie. upgraded power/suspension/brake mods) doesn't have to work as as hard as it used to, which is good.

I doubt that there are any serious MX5 racers using 17" rims.

[Aussie Stig]

Uber-5, love it though you do need the umlaut.

Yr big brakes could have possibly added 2kg per wheel. Did you weigh them and compare? The tyres you are running weigh more than stock. So I would tend to say that the final figure would be around about the same as when you started. Because the suspension, tyres and brakes can't offer weight savings, rims are the only easily changed part of unsprung weight, though I do think the effect is overstated. Perhaps a placebo effect is the over riding factor?

I would run 14's as 4.8kg is a seriously light wheel and the smaller brakes don't seem to bother NA owners. Just as an aside Mazda considered aluminium wishbones for the NB but rejected the proposal because the 5 had to remain affordable. Now that would have had a real effect on unsprung weight.

[Apu]

Aussie Stig - the stock 16" rim are a touch over 7kg each, my new 15" rims are 5.5kg. The additional difference came from the tyres. The total was about 2.8kg per wheel.

You should have a weigh of Hjt's SSR rims, they 4+kg each rim...so yes it is possible to save 3kg on the rim alone, let alone total wheel.

The issue here is rotational mass as Lokiel pointed out.

Perhaps you should try a heavy 16" on your car (I assume it you drive an NA?) and see how differently your car feels. Stock wheels should do the job.

[Lokiel]

Uber-5, love it though you do need the umlaut.

Yr big brakes could have possibly added 2kg per wheel. Did you weigh them and compare? The tyres you are running weigh more than stock. So I would tend to say that the final figure would be around about the same as when you started. Because the suspension, tyres and brakes can't offer weight savings, rims are the only easily changed part of unsprung weight, though I do think the effect is overstated. Perhaps a placebo effect is the over riding factor?

Couldn't find the umlaut at the time

The SE came with the BBK so that takes brakes out of the equation and I now run Wilwoods up front which are lighter than the BBK.

The effect of lighter rims on my "Über-5" isn't really noticeable other than the ride is no longer bone-jarring and I now no longer fear potholes but I believe that the car itself doesn't need to work as hard.

My 15x8 rims+tyres are around 1.5kg each less than before (vs OEM 17x7+tyres) which is still a significant amount of rotational mass difference.

[Hjt]

FYI,

My front wheels are 15x6.5 and weight 3.9kg

Rear wheels are 15x7 and weight 4.1kg. Total rim weight is 16kg. A tonne less than the 32kg of the Racing harts.

50% less weight in wheels alone as unsprung weight. It does help.

[bootz]

FYI,

My front wheels are 15x6.5 and weight 3.9kg
Rear wheels are 15x7 and weight 4.1kg. Total rim weight is 16kg. A tonne less than the 32kg of the Racing harts.
50% less weight in wheels alone as unsprung weight. It does help.

As he proudly states, those are very nice figures. SSR Mk2?. Will look for your pics.

I think the points that were made - Apart from rims there is no other practical way of reducing unsprung weight, also that the rim is a relatively small proportion of the total weight, not that it made no difference. Obviously if the rim is light and it looks hot you have a win/win situation.

[Hjt]

True, I will eventually put the images up. Wheels are SSR type C.

[alexpav]

Wifes NB8A with NB8B wheels