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Diff bounce with 255's on the rear of a R33 GTS-T?

slayer
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slayer Collaborator

slayer

Posted
Posted

HI guys, great forums here!

I have just bought a '93 R33 GTS-T, and want to replace the skinny stock tyres on it with some decent rubber.

I am considering 235/45 on 17s at the front (on 8" rims), and 255/40 on 17s at the rear (on 9" rims).

My two biggest concerns are that if I go with the general consensus and 235/45/R17 on the front and 255/40/R17 on the rear I will

A) get a pretty harsh ride and

B) Get into grief trying to do a hard launch or powerslide with 'diff bounce' (not the right term, but all I can think of now).

At the moment the stock tyres allow me to do fantastic, smooth powerslides and launches without the wheels bouncing up and down like crazy and costing me time (and perhaps killing the diff)... what is the likelehood of having that problem with 255/40's on the rear?

If it occurs, do I need to go to a higher profile/skinnier tyre to avoid it, or buy better shocks, or is it as the guys at BobJane suggested down the the choice of tyre (not size)?

What do the drifters use on these things, these sort of tyre setup? I dont plan to drift, but certainly want to be able to step it sideways or do a serious launch.

Any help would be appreciated! Thanks

Conrad

JimX Grand Master

JimX

Posted
Posted

I have exactly the tyre/wheel sizes that you want to upgrade to, and I only have 2 problems - 1 is the guards are too narrow on the front, I need to get them rolled or something (or buy GTR guards :D) and 2 the rear tyres are so soft they shred and leave black tyre dust all over the back of my car. Well that's not related to the size at all but I thought I'd mention it anyway :D

I don't have any problems with comfort, handling or traction with this setup. I'd say a lot of that would have to do with your shock absorbers and sway bars anyway.

slayer Collaborator

slayer

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Hi JimX,

thanks for the update - do you run stock suspension on yours? mine is totally stock at the moment, so trying to get a feel for if I will need to move to better shocks once I have this tyre setup on.

Hmm... if theres no probs with the sizes I have picked, now I just have to pick WHAT tyres to use... sheesh!

I do like the look of the Falken 451's, if you have any advice on tyres I am listening :D

JimX Grand Master

JimX

Posted
Posted

I've got Bilstein shocks in mine. It did have the factory suspension when I got it but it was totally worn out so I can't really compare the ride qualities. The steering wheel would shudder like a bastard everytime I hit a decent bump with both front wheels at the same time.

I've heard that the Japanese sports suspension (Cusco/JIC/Tein etc) are all really hard and not very comfortable for Australian roads. And unless the road is really smooth you'll be airborne a lot of the time anyway with ultra-hard suspension. I was originally after Koni adjustables but apparently they don't do a kit for Skylines yet.

For tyres I would probably go Nankang, that's what I have on the front and they seem to be a bit harder than my rear Toyo's (much less tyre dust) but seem to grip just as good. When my rears wear out I'll try Nankangs on the back too. I don't know much about Falkens because they have so many different models, but I do know that the low-end hard model that most people put on their Skylines to compliance them are pretty crap. Go for something a bit softer.

ex-static Grand Master

ex-static

Posted
Posted

Check out this thread on tyres

Tyres

I have the 25540s on the back, and 23540s on the front, its an awesome setup, and doesnt ride harsh at all, with the purchase of my new tyres i'll have a similar setup.. try and keep the profile the same.. is there any reason you want 45s on the front and 40s on the rear?

JimX Grand Master

JimX

Posted
Posted

235/45 is a closer match in height to 255/40 than 235/40 to 255/40. Here's what the profile height of each of the aforementioned will be:

235/40: 94

235/45: 105.75

255/40: 102

255/45: 114.75

So if you kept the same 40 profile front to rear, the rear tyre diameter is 8mm bigger than the front as opposed to about 4mm smaller if you got 45 for the front. I guess it's not much difference either way, but for that reason it's fine do choose either profile combination.

Personally I would get whatever size made the speedo most accurate (ie closest to stock) and then get the profile on the front that was the closest in size to the rear.

XrSiSt Grand Master

XrSiSt

Posted
Posted

The reason why i say it would be a little bit harsher would be

the less flex in the tyre wall on a lower profile tyre.

Does everyone agree or disagree with my theory/practise?

Hmm. but then again. it does depend on your shocks also.. I've

got stock shocks with about 3inch lowered springs... :D

Looks aight... just ask Ryan about the ride..

Bump and Grind all the way baby!!

MetBlue_GTST Community Regular

MetBlue_GTST

Posted
Posted

I've got 255/40 on the rear and 235/45 on the front with JIC coilovers... These coilovers are sssoooooo stiff!!!!! Lets just say they are the equivalent of an iron bar in place of the coilovers... When i jack up the car, the coilovers only push out less than 1cm... So i find the ride very harsh, but awesome round corners, feels like its on rails!!! And around the track is awesome as well...

As for diff bounce, i got a 2 way nismo LSD, and i don't notice any sorta bouncing, just wheel spin...

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