Musings - Rear wheel/tyre choice and engine revs

[ZedBed]

Some of you have same small tyres front and rear, to your engine revs/speedo ration is the 1.0. i.e. if VW say "she's gonna blow captain" at 65mph on standard tyres, that's the speed you speedo will show for those revs. Or course you'll be travelling slower in reality.

 

[mattyd72]

Modest drop on mine also but have 225 75s on the rear 185c 14 on the front. Speedo an irrelevance as its in pieces :lol:



Sent from my GT-I9100 using Tapatalk 2

 

[Humphrey]

http://gpssystems.net/accurate-gpsbased-speedometer/" onclick="window.open(this.href);return false;

 

[PIEMAN]

I'm runnin 185/55/15 all round
When speedo says 65mph sat nav is 57mph
Modest drop on mine. Adjusters on front n prob 1 spline at rear
Will my engine revs be too high when runnin at actual 60mph as it would show 68mph on speedo ?
Fatter tyres all round maybe ?
Would that be better for truer speedo reading and better for engine ?

 

[Tofufi]

I run standard rear tyres with what I believe to be a 1 spline drop. I was contemplating going up to 195/80/14s, or maybe going to 15" wheels on the rear in a bid to improve cruising speeds.

Standard fronts, too.

Even with standard rear tyres, I'm not keen on the high revs I'm getting above around 55-60mph. But mine will sit at those speeds 5 up full of camping gear all day.

My bus isn't as low as some just as I'd hate to have smaller rear tyres.

 

[john the horse]

Slams on front and 185/65/15 back, still only cruisin at 55 with the occasional blast up to 65 for a minute, OG speedo makes me look a hero, but sat nav he say no i aint.

Have to agree about the cooling revs between 3000-3500, over that the temp does rise and sitting at 4000 for too long the temp is getting at bit of an arse pincher,

dont ask how we get the rears off have just done it and need two jacks and axle stands thats with adjustable springy plates too,

i did see a link on here to a mega expensive german made fan think it was over 200 euros phew!

we were going for more power but we are slowly goin back to lock stock, less hassle.

Aguy once told me stock guys want big motors and big motor guys want stock!!!! :lol:

john the horse

 

[camit34]

here's a really great tire size calculator I use very often -

http://www.miata.net/garage/tirecalc.html

 

[ZedBed]

I run standard rear tyres with what I believe to be a 1 spline drop. I was contemplating going up to 195/80/14s, or maybe going to 15" wheels on the rear in a bid to improve cruising speeds.

Standard fronts, too.

Even with standard rear tyres, I'm not keen on the high revs I'm getting above around 55-60mph. But mine will sit at those speeds 5 up full of camping gear all day.

My bus isn't as low as some just as I'd hate to have smaller rear tyres.

If you increase the tyre size above standard with stock engine, I think you'll find the engine will get hotter as it'll be working harder than it's designed to. It's supposed to rev high so it gets max cooling and works less hard. They're just noisy beasts, in reality the revs aren't very high at all.

If you have a beefed up engine, serpentine fan belt, additional oil cooler etc etc to deal with the additional heat I guess you can lower the revs for given speed by whatever means - different gearing or bigger tyres.

My 1600 bog-standard SP seems happy to cruise at 60-65 all day long on std rear tyres (1 up, not much stuff on board). I suspect it might manage 65-70, but with no temp monitoring I'll stick to the slower speeds. If your heating is connected, from experience you can smell when it's getting too hot.

 

[quentinfarquar]

I am reading this with interest as my van is at the current state above, and I am new to all this. It has been lowered 2" at the back mainly to get it in my garage. It came with these 15" polished wheels, which I believe are porsche offset wide 5. The tyres are fairly chunky van tires and only have 165r15 on them. There isn't alot of room on the arch on one side, mainly due to the offset.

So not sure what to do for the best, how do I work out what tyre would give me stock settings on a 15" wheel. Should I be worried about it been close to the arch or is this common.