jeep wheel tyre sizes?

J

jonnydurex

New Member
finally got hold of some 17`s for my rover...search out "rover p6 burnout" on youtube if you havent seen 17`s on a rover b4...i`ve emailed the chap from there but got no answer (from the post of his car on the rolling road)..what i need to know it what tyre size will go on...i`m guessing 205/40/17 or 205/45 17 but as the 40`s are twice the price i`m hoping the 45`s will fit

i`m not bothered about rolling radius or speedo being out...will go behind another car and just put tippex where 30,40,50 and 70 are! and if the gearing really is that bad a 5 sp sd1 box will sort it
 
just had a reply from the fella on youtube (mentioned above)...says he fitted 225/50/17`s....thought the widest would be 205 at a push....must be the reduced tyre wall bulge due to the low profile...think i`ll get a part worn one first...just to be on the safe side!! :D
 
No idea if they'll clear suspension and the D post but based on the standard tyres being 165/14 then the 225/50/17 will be a slightly bigger rolling radius, you'll be doing roughly 75mph when the speedo says 70, which probably isn't that bad, I'd use a gps to calibrate rather than another car, speedo's are always out a bit, GPS is pretty much the most accurate method. You'll probably find the speedo was over-reading anyway so it will be about right with the 225's on.:D

Can't wait to see some pics with them on, that's roughly the size I want to use on mine. Which alloys did you get ?
 
my wheels are ebay number 120268061472,i didnt win them,i bought them for £150 a day b4 the auction finished,guess he got a "friend" to put in a stupid bid,was gonna tell him to withdraw them but wanted to see what they went for...think i got a bargain....the one tyre is a new goodyear and is worth about £80 on its own (going for £100 buy it now on ebay!)

think i`ll be going inbetween and seeing how a 215/50/17 looks...plus the calculater on tyre bible gets it as a pretty much spot on rolling radius match...i was thinking of lowering it but the one on you tube looks so good :D
 
looked at the bid history for those wheels..did notice the "friend" who won my wheels on ebay did put two other bids in to push the price up...crafty sods lol
 
Those wheels look really nice! I want to see some pics on the car!

Before you put tyres on them, measure the actual offset. Ie measure the total width across the rim and divide by 2 to get the amount the wheel would stick out each side of the centre line for zero offset. Then measure from the hub mating face of the wheel out to the back rim. The difference is the offset - if the hub to rim is greater then the offset is into the car, hub to rim smaller the offset is out from the car - up to you which you call positive and which negative! Width of the rim is irrelevant to this calculation - you're just trying to measure how far the centre line of the rim is offset from the hub mating face (hence the term offset!)

My reckoning is that the ideal offset to allow the widest possible tyre at full rolling radius is 53mm into the car.

I got my handy tyre calculator out and 205/55 is virtually a perfect match on rolling diameter, 215/55 is plus 2%, 215/50 is minus 1%, 215/45 is minus 5%, 225/50 is spot on, 225/45 is minus 3%.

With 205/55 you would need the offset to be spot on not to have any clearance issues. Reducing the rolling diameter improves clearance at the expense of lowering overall gearing (it pulls the wide part of the tyre backwards away from the pinch point behind the D post), so if you were going to go for 215 then I'd be inclined to go for 215/45. I'm pretty sure you'd have no chance with 225's.

Important to try a scrap tyre first before committing too many pennies! And don't forget that with the de dion rear axle the rear track changes with supension compression - so try it slightly jacked up and then with a ton of lead in the boot! You never know, a get out of jail card might be new full ride height rear springs, or new lowered rear springs, depending which way you need to win clearance.

If the car is too thrashy afterwards you could always fit an LT77 (ex SD1) or R390 (later version of LT77 in Discoveries, Sherpa vans etc etc) 5 speed overdrive manual or ZF HP22 4 speed overdrive auto to bring the overall gearing back up.

Chris
 
in the youtube comments he states what size spacers were used so will save me doing all the measuring

not sure why he went to M11 wheel studs instead of sticking with the 7/16..have trial fitted and the studs seemed long enough

Think i`m gonna get some spigot rings machined up to make sure the spacers and wheels are located properly,only ones i can find ready made are over an inch thick and $200 plus postage from the states :(
 
If you need spacers to achieve the best possible offset then make sure you spec them after you've measured up the actual offset on the wheels.

Since spacers are true unsprung weight (very bad for suspension, ride, handling etc) it's worth going to a bit of trouble to make them as light as possible. A 7000 series aluminium would be ideal - very light with the strength and wear resistance of steel. You'll see decent bicycles made out of this; it's actually an alloy of Aluminium with trace Copper and Zinc. Failing that a 6000 is probably OK.

Chris
 
You must log in or register to reply here.
Back
Top